The value of acceleration due to gravity at a point P inside the earth and at another point Q outside the earth is g/2 .(g being acceleration due to gravity at the surface of the earth). Maximum possible distance in terms of radius of earth R between P and Q is:
a. 2R
b. 2R(√2+1)
c. R/2 (2√2-1)
d. R/2 (2√2+1)