Question

Which of the following statements is correct?

Answer 1

The answer would be C, "The earth is heated by terrestrial radiation."

Terrestrial radiation is a factor in what heats up the earth and it's a major factor in the study of global warming. 

Answer 2

The following answer is correct :

The earth is heated by terrestrial radiation.

Terrestrial radiation is a radiation emitted by naturally radioactive materials present on Earth including uranium, thorium etc. Solar radiation produced from the sun also heats up the environment but not directly. But rather it is heated by the terrestrial radiation that the planet itself emits.