Answer:
A.) Change only the coefficients
Step-by-step explanation:
An equation is balanced when there is an equal quantity of each type of element on both sides of a reaction. When balancing an equation, the only way to manipulate the amounts of each element is by changing the coefficient values. The coefficients alter the amount of each molecule in the reaction.
The subscripts cannot be altered. If you were to change the subscripts, you would be altering the amount of atoms in a particular molecule.