Context: This passage describes a chemical reaction. Read the passage. Then, follow the instructions below.
Did you know that lightning helps provide nutrients to plants on Earth? When lightning strikes, the air around it becomes extremely hot. This leads to the formation of nitric oxide from the nitrogen and oxygen gases in the air. Nitric oxide plays an important role in helping plants grow.
Complete the sentence.
In this chemical reaction, nitric oxide is a ().
A. reactant
B. product
Select the correct answer from the provided options and reply with the letter associated with it.

B