In the first sentence, the phrase what's called the greenhouse effect presents a/n

If the queries are related to these answers, then greenhouse effect is in the second number.

1.       C. Human activity. Human activity is not a natural cause of climate change. 
2.       C. absorption and radiation of energy in the atmosphere. The carbon cycle.
Thus, greenhouse effect is the absorption and radiation of energy in the atmosphere. The carbon cycle.
3.       B. Gravitational attraction between Earth, the Moon, and the Sun. These are influences by the gravitation forces of attraction these three heavenly bodies are continuously on the process. 
4.       B. Mid-Atlantic. Somewhere in Florida. 
5.       C. the long-term average of weather variations in a specific area.