In Newton's law of universal gravitation, the magnitude of the gravitational force between two point masses is $F=G\frac{m{}_{1}m{}_2}{r^2}$. Which two factors determine the value of $F$ for a given pair of objects?

• A. The acceleration due to gravity $g$ at the surface and the objects' speeds
• B. The electric charges on the objects and the distance $r$
• C. The two masses $m{}_1$ and $m{}_2$, and the distance between their centers $r$
• D. The volumes of the objects and the temperature of the surrounding space

Answer: (C)