Question: Which of the following actions will increase the gravitational force between two masses, m_{1} and m_{2}, by the greatest amount?

  Options: 
 A. Halve the mass of m_{1} and halve the distance between m_{1} and m_{2}.
 B. Halve the mass of m_{1} and double the distance between m_{1} and m_{2}.
 C. Double the mass of m_{1} and halve the distance between m_{1} and m_{2}.
 D. Double the mass of m_{1} and double the distance between m_{1} and m_{2}. 
Answer: C