D is correct. Damodar was known as the sorrow of Bengal, as it would flood the plains of Bengal and cause widespread destruction annually. It would flood Hooghly and Howrah almost every year. However, since the construction of dams, the havoc has been tamed to some extent.

A is incorrect. Gandak is a tributary of Ganga flowing into Nepal, and does not pass through Bengal.

B is incorrect. Son also does not flow through Bengal, and is southern tributary of Ganga which flows through Central India.

C is incorrect. Kosi causes massive flooding in Bihar, but does not impact West Bengal lands.