Which of the following rivers fall into the Bay of Bengal?

India's rivers are broadly grouped by which sea they drain into: most peninsular and Himalayan rivers follow the general west-to-east tilt of the land and reach the Bay of Bengal, while a smaller set of peninsular rivers, together with the Indus system on the western flank, drain instead into the Arabian Sea; a few interior tracts have inland drainage reaching neither sea.

Checking each option against its actual outfall:

Narmada flows west through a rift valley between the Vindhya Range to the north and the Satpura Range to the south, while Tapti flows west through a separate, parallel rift valley south of the Satpura Range, bounded by the Ajanta-Satmala hills; both rivers reach the Arabian Sea via the Gulf of Khambhat. The Indus is a separate Himalayan-origin system that flows south-west through Pakistan to the Arabian Sea near Karachi. All three therefore lie outside the Bay of Bengal drainage.

Subarnarekha is the only river among these four that falls into the Bay of Bengal.