Explanation
The best choice to fill up the blank in the sentence is B: Wishful.
"It is wishful thinking on the part of India that the US will fight the battle to eliminate terrorism from India."
The word "wishful" means having or expressing a desire or hope for something to happen, but without any realistic expectation of fulfillment. In the given sentence, India's expectation of the US fighting a battle to eliminate terrorism from India is unrealistic and unlikely to happen, hence the word "wishful" is the appropriate choice.
