2016 Cayley Problem 9

Grace writes a sequence of 20 numbers. The first number is 43 and each number after the first is 4 less than the number before it, so her sequence starts 43, 39, 35, \ldots . How many of the numbers that Grace writes are positive?

\textbf{(A)}\ 11\quad \textbf{(B)}\ 9\quad \textbf{(C)}\ 13\quad \textbf{(D)}\ 15\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 Cayley contests here.