Explanation:
The force acting between two masses is given by :
........(1)
Where
G is the universal gravitational constant
are masses
d is the distance between two masses
It is clear from equation (1) that the gravitational attraction between the bodies always increases if the masses of bodies increases and when the separation between masses decreases.
So, the correct answer is "the masses increase, and the distance between the centers of mass decreases". This is because the force of gravitation is directly proportional to the masses and inversely proportional to the separation.