, 2015

In trapezium $PQRS$, the sides $PQ$ and $SR$ are parallel. Angle $RSP$ is $120^\circ$ and $PS = SR = \frac{1}{3}PQ$. What is the size of angle $PQR$?

(A) $15^\circ$ (B) $22.5^\circ$ (C) $25^\circ$ (D) $30^\circ$ (E) $45^\circ$