The tendency of two masses alone in the universe to drift together is a result of
a. fission.
b. friction.
c. fusion.
d. gravity.

It is as a result of gravity.  (D)

This is as stated by Newton's law of universal gravitation. That two objects in the universe attract one another with a force that is proportional to the product of their masses and inversely proportional to the square of the distance apart.

The constant of proportionality is the Universal Gravitational Constant.

G = 6.673 × 10⁻¹¹ Nm²kg⁻²

Idk just need points

It maybe because uranus is made of gas but uranus has a solid core in the middle