Correct option is A

The correct answer is (a) Binomial theorem formula:

The term involving ( H^5 T^4 ) is ( X H^5 T^4 )
According to the binomial theorem formula, the coefficient of ( H^5 T^4 ) is given by ( \binom{9}{4} = \frac{9!}{4!(9-4)!} ) Calculating the value:

Answer=126