AMC 8 2015 Problem 2

Point $O$ is the center of the regular octagon $ABCDEFGH$ , and $X$ is the midpoint of the side $\overline{AB}.$ What fraction of the area of the octagon is shaded? $\textbf{(A) }\frac{11}{32} \textbf{(B) }\frac{3}{8} \textbf{(C) }\frac{13}{32} \textbf{(D) }\frac{7}{16} \textbf{(E) }\frac{15}{32}$