Option 1: This option is not correct. It suggests that acceleration due to gravity is directly proportional to the mass of the Earth. However, this is not the case. The acceleration due to gravity is independent of the mass of the object being accelerated.

Option 2: This option is correct. It states that the acceleration due to gravity `g` is related to the universal gravitational constant `G` by the equation g = GM/R^2. This equation shows that the acceleration due to gravity depends on the mass of the Earth (M) and its radius (R).

Option 3: This option is not correct. It suggests that the acceleration due to gravity is directly proportional to the distance between the object and the center of the Earth. However, the acceleration due to gravity actually decreases with distance from the center of the Earth.

Option 4: This option is not correct. It suggests that the acceleration due to gravity is directly proportional to the square of the radius of the Earth. However, the acceleration due to gravity is inversely proportional to the square of the distance between the center of the Earth and the object.