Question

the thickness of a terrestrial planets atmosphere is determined primarily by its mass and the tilt of its axis. its mass and brightness. its mass, temperature, and amount of geological activity. its mass and the number of its moons.

Explanation:

The mass of a terrestrial planet affects its gravitational pull on the atmosphere. Higher - mass planets can hold more gas. Temperature influences the speed of gas molecules; higher temperatures can cause gas to escape more easily. Geological activity can release gases into the atmosphere. The tilt of the axis, brightness, and number of moons have less direct impact on atmospheric thickness.

Answer:

its mass, temperature, and amount of geological activity.