Answer : 3. "Echinoderms"
Explanation :

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.