Let vA,vB,MA,MB and RA,RB be the escape velocities, masses and radii of planet A and B, respectively. As we know that, v=2gR=R22GM⋅R=R2GM where, G is the gravitational constant. ⇒v∝RM Since, vA=vB∵RAMA=RBMB⇒MARB=MBRA or M1R2=M2R1 Hence, option (b) is the correct.