JEE Math Practice Question

$$r$$ and $$n$$ are positive integers $$\,r > 1,\,n > 2$$ and coefficient of $$\,{\left( {r + 2} \right)^{th}}$$ term and $$3{r^{th}}$$ term in the expansion of $${\left( {1 + x} \right)^{2n}}$$ are equal, then $$n$$ equals

1. A.$$3r$$
2. B.$$3r + 1$$
3. C.$$2r$$
4. D.$$2r + 1$$