Fixed Costs and Variable Costs
Which of the following is an example of a variable cost?
a. Insurance premium for fire insurance on the factory building
b. The salary of the company president
c. Wood used to make custom tables
d. Rent for use of a storage warehouse
e. Depreciation on the factory building

My answer is c, because the wood can vary in price from store-to-store as well as lumber prices changing. Am I on the right track?

Thank you.