Question

how does convection occur in the troposphere?
the suns rays heat earths surface.
warm air rises and cool air sinks.
the warm ground heats the air above it.
the suns electromagnetic waves reflect off clouds.

Explanation:

Convection is a process of heat transfer in fluids (liquids and gases). In the troposphere (the lowest layer of the Earth's atmosphere), when the ground is heated (by the Sun's rays - which is radiation, but once the ground is hot), the air in contact with the warm ground gets heated. Warm air is less dense than cool air. According to the principle of buoyancy, less - dense (warm) air rises. As the warm air rises, the cooler (more dense) air from the surrounding (and above in some cases) sinks to take its place. This continuous cycle of warm air rising and cool air sinking is the mechanism of convection in the troposphere.
The first option is about electromagnetic waves (radiation), the second is about conduction (heat transfer through direct contact, but here it's more about the movement of air masses), and the fourth is again about radiation (Sun's rays heating the surface is radiation, not convection).

Answer:

Warm air rises and cool air sinks.