Two Long Bar Magnets Are Aligned So That North Poles

Multiple Choice

Two long bar magnets are aligned so that north poles face each other. The magnets are separated by 1 cm, and a repulsive force between the north poles is 0.04 N. When the separation is increased to 2 cm the force will be

A) 0.010 N.
B) 0.020 N.
C) 0.025 N.
D) 0.40 N.
E) 0.050 N.