Final answer:
Halve the distance between the objects.
Step-by-step explanation:
The correct answer to the question is B) Halve the distance between the objects. In physics, the force of gravity between two objects is inversely proportional to the square of the distance between them. This means that if you halve the distance between two objects while keeping their masses constant, the gravitational force between them will increase by a factor of four. Increasing the distance between the objects, as in option A, will cause the gravitational force to decrease.