The correct answer is (b) Sal.
Explanation: The Arabari forests of Bengal are primarily known for their large population of Sal trees.
Why other options are incorrect:
(a) Teak:
While teak is a valuable hardwood, it is not the dominant tree species in the Arabari forests.
(c) Bamboo:
Although bamboo can be found in certain areas, it is not the primary tree species dominating the Arabari forests.
(d) Mangrove:
Mangroves are typically found in coastal areas near saltwater. The Arabari forests are inland, so they are not suitable for mangrove growth.