2016 Gauss 8 Problem 8

Gaby lists the numbers 3, 4, 5, 6, 7, 8, and 9. In her list, the ratio of the number of prime numbers to the number of composite numbers is

\textbf{(A)}\ 3:4\quad \textbf{(B)}\ 5:2\quad \textbf{(C)}\ 2:5\quad \textbf{(D)}\ 3:7\quad \textbf{(E)}\ 1:6

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 Gauss contests here.