A straight rod of length L extends from x=a to x=L +a. The gravitational force is exerted on a point mass 'm' at x=0, if the mass per unit length of the rod is A+Bx2 is given by.
A. Gm[A(1/a+L−1/a)−BL]
B. Gm[A(1/a−1/a+L)+BL]
C. Gm[A(1/a+L−1/a)+BL]
D. Gm[A(1/a−1/a+L)−BL]
