human
Question: A gasoline is advertised as "releasing fewer pollutants" when it is used in cars. For this claim to be accurate, what has most likely happened to the gasoline?

Choices:
A) Its acidity has been increased.
B) More oxygen has been dissolved in it.
C) Impurities have been removed.
D) Its molecules have higher chemical energies.
gpt
The correct answer is 2: Impurities have been removed..