Given the integers $r > 1,n > 2$ and coefficients of $(3r)^{th}$ and $(r+2)^{nd}$ terms in the binomial expansion of $(1+x)^{2n}$ are equal then

Question

$\begin{array}{1 1}(A)\;n=2r\\(B)\;n=3r\\(C)\;n=2r+1\\(D)\;\text{None of these}\end{array}$