According to Newton's law of universal gravitation, what is the magnitude of the gravitational force exerted on an object of mass $m$ by a second object of mass $M$ at a center-to-center separation $r$?

• A. $F=\frac{GM}{r^2}$
• B. $F=GMm{r}^2$
• C. $F=\frac{GMm}{r^2}$
• D. $F=\frac{GMm}{r}$

Answer: (C)