According to Newton's law of universal gravitation, if the distance between two point masses is doubled while their masses remain constant, how does the magnitude of the gravitational force change?

• A. It becomes twice as large (multiplied by $2$).
• B. It becomes four times as large (multiplied by $4$).
• C. It becomes one-half as large (multiplied by $\frac{1}{2}$).
• D. It becomes one-fourth as large (multiplied by $\frac{1}{4}$).

Answer: (D)