In Newton's law of universal gravitation, $F=G\frac{m_1{m}_2}{r^2}$, how does increasing the masses affect the gravitational force between two objects if the distance $r$ remains constant?

• A. The gravitational force increases in direct proportion to the product $m_1{m}_2$.
• B. The gravitational force increases in proportion to ${m_1{m}_2}^2$.
• C. The gravitational force increases in direct proportion to the sum $m_1+m_2$.
• D. The gravitational force is independent of mass and depends only on $r$.

Answer: (A)