AMC 10 2014a Problem 8

Which of the following numbers is a perfect square? $\textbf{(A)}\ \dfrac{14!15!}2 \textbf{(B)}\ \dfrac{15!16!}2 \textbf{(C)}\ \dfrac{16!17!}2 \textbf{(D)}\ \dfrac{17!18!}2 \textbf{(E)}\ \dfrac{18!19!}2$