The lens which is thinner at the middle than the edges is __________.

किस विकल्प में सभी अशुद्ध शब्द हैं?

Among Nature’s most intriguing phenomena are the partnerships formed by any different species. The name used for these relationships, Symbiosis, comes from Greek meaning "living together". Not all symbiotic relationships are the same. There are some called commensal relationships, in which one partner gains a benefit while the other gains little or none but is not harmed. One example is the relationship between two types of fish remoras and sharks. The remora, which is long and often striped, attaches itself to a shark (sometimes to another type of fish or a whale), using a sucker on its head. When the shark makes a kill, the hitchhiker briefly detaches itself to feed on the scraps. Another type of symbiotic relationship is parasitism, in which one partner benefits at the expense of others. Ticks and tapeworms are among familiar parasites. 

The third type of symbiotic relationship, called mutualism, is a true partnership in which both partners benefit. The relationship may be limited as when zebras and wild best graze together on the vast African grasslands. Each species can survive on its own, but together their chances of detecting predators are improved because each contributes a specially keen sense. (Zebras have the better eyesight;  wild beast, hearing and sense of smell). In a few cases partners are so interdependent that one cannot survive without the other. Most mutualistic relationships probably lie some where in between

Commensal relationship is a type of symbiosis in which the relationship is beneficial 

You have eight brief passages with 10 questions following each passage. Read the passages carefully and choose the best answer to each question out of the four alternatives 

A farmer accompanied by his young son was driving his ass to the market in the hope of selling the ass for a good price. On the road, they met a bevy of girls who laughed and exclaimed, “See this pair of fools ? They are trudging along the dusty road, when they can be riding !” The man thought that there was sense in what they were saying. So he mounted his son on the ass and he walked at the side. Presently, they met some of his old friends, who greeted him and said, “You’ll spoil your son, by letting him ride while you toil along on foot! Make him walk. It’ll be good for him.” The farmer followed their advice and took his son’s place on the back of the ass while the boy trudged along behind. They would not have gone far, they were seen by women and children. The farmer heard them say, “What a selfish old man ! He rides in comfort, but lets his poor little fellow walk the distance.” So he asked his son to get up behind him. Further along the road, they met some travellers. They asked the farmer whether the ass was his property or was it hired for the purpose. The farmer told them that he was taking his ass to the market to sell it. The travellers said, “Good Heavens ! With the load like this, the poor beast will look exhausted and no one would like to purchase him. Why don’t you carry him.” Immediately, the farmer got off the ass, tied its legs with the rope and slung him on a pole and carried him in between them. This was such an absurd sight that people laughed at it. They called the farmer and his son lunatics. They had then reached a bridge over a river. Frightened by the noise around, the ass struggled, kicked, broke the pole, fell into the river and died. The farmer returned home vexed and ashamed. In trying to please all, he in fact, had pleased none and he had lost the ass in the transaction. 

The travellers asked the farmer to carry the ass because  

You have brief passages with 10 questions following each passage. Read the passages carefully and choose the best answer to each question out of the four alternatives

There is a general consensus that ‘International Understanding’ need to be taught as a separate subject at the school stage as that would add to the curricular load which is already too heavy. Instead it should be woven into the curriculum and the numerous opportunities that present themselves while teaching normal school subjects may be intelligently and imaginatively used by the teacher to promote International Understanding.

The school subjects which can be most profitably used for this purpose are History, Geography, Civics, Economics, Sociology, Political Science, Social Sciences, Languages as well as Physical and Life Sciences. However, at the higher education level, international education can be prescribed as a separate subject of study. In fact, the present situation in India broadly conforms to this consensus so far as the school stage is concerned.

At the under-graduate and the post-graduate levels, courses of study in subjects like History, Geography, Economics, Political Science, International Relations, International Law and International Organization have been prescribed by most of the universities and these contain content which has a direct or indirect bearing on promoting UNESCO ideals

On reading Para 1, it can be inferred that

A trader allows a trade discount of 20% and a cash discount of $$6{1\over4}\%$$ on the marked price of the goods and gets a net gain of 20% of the cost. By how much above the cost should the goods be marked for the sale? 

Select the most appropriate meaning of the given idiom.
 Cover up 

Choose the word that is opposite in meaning to the given word.

Algid