In triangle ABC,BR=RC,CS=3SA, and \displaystyle\frac{AT}{TB}=\frac pq. If the area of \triangle{RST} is twice the area of \triangle{TBR}, then \displaystyle\frac pq is equal to
Answer Choices
A. \frac21
B. \frac83
C. \frac52
D. \frac74
E. \frac73