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

Which principle states: "geologic processes taking place on earth today operated similarly in the past and can be used to explain past geologic events"? a. lateral continuity

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction