Correct option (a) Between A and B gravitational field strength is zero.
(b) Between A and B gravitational potential is constant
(c) There will be two point one lying between B and C and other lying between C and infinity where gravitational field strength are same.
Explanation :
As there is no mass inside B, So, field between A to B is zero, i,e,. potential between A to B is constant.
Potential between B and C is not zero at any point.