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.

This is a correct statement regarding sexually transmitted diseases (STD).

Statement A: Sexually transmitted diseases (STD) are infections transmitted from an infected person to an uninfected person through sexual contact.

Statement B: HIV, HPV and Hepatitis B virus is responsible for STD.