please answer this question with a reason. i have attached the question.

The answer is a=1. There is a rule named L-Hospital rule by which you can solve any limit easily. In this problem, thus rule should be applied. It tells that whenever a limit comes In the form 0/0 or infinity/infinity then apply derivative on both numerator and denominator with respect to the given variable. Hence now put the value of the constant which tends to from the variable.