question_answer

For \[a\in R\] (the set of all real numbers), \[a\ne -\,1,\] \[\underset{x\to \infty }{\mathop{\lim }}\,\,\,\frac{({{1}^{a}}+{{2}^{a}}+....+{{n}^{a}})}{{{(n+1)}^{a-1}}[(na+1)+(na+2)+....(na+n)]}=\frac{1}{60}\]

A)  5                                

B)  7

C)  9                                

D)  11

E)  None of these