If there is a term containing $x^{2r}$ in $(x+\large\frac{1}{x^2})^{n-3}$ then

Question

$\begin{array}{1 1}(A)\;\text{n-2r is a positive integral multiple of 3}\\(B)\;\text{n-2r is even}\\(C)\;\text{n-2r is odd}\\(D)\;\text{none of these}\end{array}$