A vehicle is travelling along concave road then along convex road of same radius of curvatures at uniform speed. If the normal reactions on the vehicle as it crosses the lowest point of concave surface, highest point of concave surface, highest point of convex surface are `1.5 xx 10^(4) N, 3 xx 10^(3) N` respectively, then the mass of vehicle is `(g = 10 m//s^(-2))`.
A. 400 kg
B. 450 kg
C. 800 kg
D. 900 kg