Two Point Masses M and M Are Separated by a Distance

Multiple Choice

Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change?

A) The force will be one-third as great.
B) The force will be one-ninth as great.
C) The force will be three times as great.
D) The force will be nine times as great.
E) It is impossible to determine without knowing the numerical values of m, M, and d.