Context: This passage describes a chemical reaction. Read the passage. Then, follow the instructions below.
To help relieve pain during a dental visit, a dentist may give a patient nitrous oxide. Nitrous oxide is made in factories by carefully heating ammonium nitrate. At 170°C, ammonium nitrate breaks down and forms a mixture of nitrous oxide gas and water vapor. After the mixture is collected, the water vapor is separated from the nitrous oxide gas.
Complete the sentence.
In this chemical reaction, nitrous oxide is a ().
A. reactant
B. product
Determine the correct option from the provided choices and reply with its corresponding letter.
Answer: B