Final answer:
The greenhouse effect is primarily caused by the re-emission of infrared radiation from the Earth's surface that is then absorbed and re-radiated by greenhouse gases in the atmosphere, warming the planet. The correct option is (c).
Step-by-step explanation:
The greenhouse effect is primarily due to the re-emission of infrared radiation by the atmosphere. When sunlight reaches the Earth, it is absorbed by the surface and then re-emitted as infrared radiation due to the cooler temperature of the Earth compared to the Sun.
This re-emitted infrared radiation is subsequently absorbed by greenhouse gases like carbon dioxide (CO2), methane (CH4), water vapor (H2O), nitrous oxide (N2O), and ozone (O3). These gases then re-radiate the heat in all directions, which includes sending some of it back to the Earth's surface, thereby warming it more than if the atmosphere did not trap the heat.