Final answer:
The balanced equation is A. 2C3H8 + 7O2 -> 6CO2 + 8H2O.
Step-by-step explanation:
The balanced equation for the reaction is A. 2C3H8 + 7O2 -> 6CO2 + 8H2O. In this equation, the number of atoms of each element is the same on both sides. For example, there are 6 carbon atoms on the left side and 6 carbon atoms on the right side. This indicates that the equation is balanced.