Fact 1: Operating an automobile usually requires fossil fuels. Fact 2: Global warming is caused largely by fossil fuel use. Given the two facts above, what contributes to global warming?

Available choices:
[I] using wind farms.
[II] recycling.
[III] burning coal.
[IV] Greenhouse gases.
[V] operating an automobile.
[VI] chlorofluorocarbons.
[VII] Greenhouse gasses.
[VIII] nuclear energy.
Answer:
[V]