Context: This passage describes a chemical reaction. Read the passage. Then, follow the instructions below.
Gasoline provides the energy that powers many car engines. In an engine, gasoline and oxygen are mixed together and burned, creating carbon dioxide gas and water vapor. This process releases energy that the engine uses to turn the wheels, making the car move.
Complete the sentence.
In this chemical reaction, carbon dioxide is a ().
A. reactant
B. product
Select the correct answer from the given choices and respond with the letter of the chosen option.

B