A projectile is projected with velocity

A projectile is projected with velocity kv_e  in vertically upward direction from the ground into the space. (v_e is escape velocity and k<1) . If air resistance is considered to be negligible then the maximum height from the centre of earth to which it can go, will be : (R = radius of earth)

(a)   R/k² +1                             (b) R/k² -1

(c)     (b) R/1 – k²                       (d) R/k + 1

Answer: c