If A and B are coefficients of $x^r$ and $x^{n-r}$ respectively in the expansion of $(1+x)^n$ then

Question

$\begin{array}{1 1}(A)\;A=B\\(B)\;A\neq B\\(C)\;A=\lambda B\text{ for some }\lambda\\(D)\;\text{None of these}\end{array}$