The best answer is option (A) - hillside deforestation. By reducing vegetative
cover upstream in the hills, run-off and discharge into rivers is significantly
enhanced during heavy rainstorms increasing the threat of flooding downstream.
The loss of natural vegetation in the delta (D)will not help the situation but
it is not as significant as (A). Similarly, the increasing severity of monsoons
(C) may be happening with global warming but the removal of trees is having the
most dramatic impact. Irrigation diversion projects (B) actually reduce the risk
of flooding as more water is consumed and it's path is managed by human built