The land connectivity India has with her neighbouring countries is less and is often through inhospitable regions. Hence, land is not a prominent means by which India’s trade happens. (Thus, option A. and option B. are ruled out)

Sea alone can’t suffice to transport India’s exports, which include perishable materials which can only be transported through the air. (Thus, option D. is ruled out).

Hence, option C. Sea and Air is the answer.