Final answer:
Gravitational force between two objects is governed by Newton's universal law of gravitation, being directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Step-by-step explanation:
The question you've asked is about the factors that affect gravitational force. The gravitational force is indeed dependent on certain factors. According to Newton's universal law of gravitation, the force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. In essence, options A and D provided are incorrect because the force is not proportional to the sum of the squares of their masses nor to the square of the distance, respectively. Option C is also incorrect because the force does not depend on density directly, but rather mass. Option B is a special case of Newton's law when one of the masses is the Earth itself; the gravitational force then depends on the mass of the Earth and the distance to its center.
Further, the gravitational force is always attractive, which means regardless of the shape or the composition of the objects, as long as they have mass, they will exert gravitational force on each other. It is also worth noting that on larger astronomical scales, gravity becomes the dominant force shaping the orbits and the motion of celestial bodies. Additionally, in the field of general relativity, the curvature of space and the slowing of time are influenced by the presence of massive bodies.