Let f:[−1,2]→[0,∞) be a continuous function such that f(x)=f(1−x) for all x∈[−1,2] . Let R1=∫−12xf(x)dx , and R2 be the area of the region bounded by y=f(x) , x=−1 , x=2 , and the x-axis. Then -
[JEE(Advanced) 2011]
(A) R1=2R2
(B) R1=3R2
(C) 2R1=R2
(D) 3R1=R2