Context: This passage describes a chemical reaction. Read the passage. Then, follow the instructions below.
Candles can be made from beeswax, the substance bees use to build honeycombs. As a beeswax candle's string, or wick, burns, the wax melts and rises up the string. The wax combines with oxygen in the air, forming carbon dioxide and water. This process releases energy in the form of light and heat.
Complete the sentence.
In this chemical reaction, beeswax is a ().
A. reactant
B. product
Choose the right answer from the options and respond with its letter.

A