Answer:
Group A.
Explanation:
The bigger 2 objects are, the more gravitation they exert upon each other. However, since size is unknown, you can assume that group A has stronger gravitation, since 2 equal-size objects put closer together have a stronger pull than 2 objects placed far apart.
Think about the earth orbiting the sun. It's in a good zone of not flying into the sun and also not flying away. If it got substantially closer, it would eventually just run straight into the sun.
