2019 Pascal Problem 19

There are six identical red balls and three identical green balls in a pail. Four of these balls are selected at random and then these four balls are arranged in a line in some order. How many different-looking arrangements are possible?

\textbf{(A)}\ 15\quad \textbf{(B)}\ 16\quad \textbf{(C)}\ 10\quad \textbf{(D)}\ 11\quad \textbf{(E)}\ 12

If there are no answer choices shown, enter a numerical answer.

Full credit to this problem is given to the CEMC, you may view all Pascal contests here.