Final answer:
Doubling the mass of one planet and decreasing the distance by half will have a greater impact on increasing the force between the planets.
Step-by-step explanation:
The force between two planets is given by Newton's law of universal gravitation. According to this law, the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Therefore, doubling the mass of one planet would have a greater impact on increasing the force between the planets, as the force is directly proportional to the mass of the planets.
On the other hand, decreasing the distance by half would result in a greater increase in the force between the planets, as the force is inversely proportional to the square of the distance.
Learn more about Factors affecting the force between two planets