Square pyramid A B C D E has base A B C D, which measures 3 \mathrm{~cm} on a side, and altitude \overline{A E} perpendicular to the base, which measures 6 \mathrm{~cm}. Point P lies on \overline{B E}, one third of the way from B to E; point Q lies on \overline{D E}, one third of the way from D to E; and point R lies on \overline{C E}, two thirds of the way from C to E. What is the area, in square centimeters, of \triangle P Q R ?
Answer Choices
A. \dfrac{3 \sqrt{2}}{2}
B. \dfrac{3 \sqrt{3}}{2}
C. 2 \sqrt{2}
D. 2 \sqrt{3}
E. 3 \sqrt{2}