The correct answer is a) Sardine.
Sardine is the most important marine fish caught in Kerala. It is a small, oily fish that is found in schools in the Indian Ocean. Sardine is a popular food fish and is also used to make fish oil and fishmeal.
Mackerel is a medium-sized, oily fish that is found in schools in the Atlantic Ocean. Mackerel is a popular food fish and is also used to make fish oil and fishmeal.
Tuna is a large, oily fish that is found in the Pacific Ocean. Tuna is a popular food fish and is also used to make fish oil and fishmeal.
Pomfret is a small, white fish that is found in the Indian Ocean. Pomfret is a popular food fish and is also used to make fish oil and fishmeal.
Sardine is the most important marine fish caught in Kerala because it is a popular food fish and is also used to make fish oil and fishmeal. Mackerel, tuna, and pomfret are also important marine fish caught in Kerala, but they are not as important as sardine.