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.

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 option that is not a seafood fish of India is:

(C) Echinoderms

Explanation:

Echinoderms, such as sea cucumbers and starfish, are not fish. They belong to a different phylum (Echinodermata) and are not typically consumed as seafood fish.

On the other hand:

Surmai is a type of kingfish and is a seafood fish commonly found in Indian waters.

Udanmin appears to be a misspelling, and without clarification, it's not clear what specific fish it refers to.

Hilsa is a type of herring and is a well-known and widely consumed seafood fish in India.

Therefore, the correct answer to the question is (C) Echinoderms.