(C) Spinal cord

Vertebrae are part of the spinal column, also known as the backbone or spine. The spinal column is a bony structure that encases and protects the spinal cord, which is a crucial component of the central nervous system. The spinal cord is responsible for transmitting signals between the brain and the rest of the body, allowing for communication and coordination of various bodily functions.

The average salinity of sea water is 3.5% or 35 parts per thousand. In other words, for every 1 litre of sea water there is 35 grams of dissolved salts (NaCl) .

The social animal among the options is:

(A) Bee

Explanation:

Bees are known for their highly organized and social behavior. They live in colonies where individuals have specific roles such as workers, drones, and a queen. They communicate with each other, work together for the common good of the colony, and have a complex social structure. In contrast, mosquitoes, bur (assuming it refers to burrowing animals), and domestic flies are not typically considered social animals in the same way as bees. Bees, especially honeybees, are well-known for their intricate social organization and cooperation within the colony.

Acetylene is the only fuel gas suitable for gas welding because of its favourable flame characteristics of both high temperature and high propagation rates. Other fuel gases, such as propane, propylene or natural gas, produce insufficient heat input for welding but are used for cutting, torch brazing and soldering.

Low pressure – when reading of the barometer is lower than inHg, this is considered as low air pressure, which is associated with warm air and rainstorm. So, clearly, a falling barometer indicates bad weather is ahead.

The main function of epithelial tissue is:

(C) Defense

Explanation:

Epithelial tissue serves as a protective covering for the body and its organs. It acts as a barrier that helps prevent the entry of pathogens and other harmful substances. Epithelial cells are tightly packed and form continuous sheets, providing a protective layer on the body surfaces, both internal and external. This protective function is essential for defending the body against infections and maintaining its integrity. Therefore, option (C) Defense is the correct answer.