Indicate whether each of the following costs is most likely a fixed cost or a variable cost

Question:

Indicate whether each of the following costs is most likely a fixed cost or a variable cost by writing fixed” or” variable” in the space provided.
______ a. Assembly labor.
______ b. The cost of material used in production.
______ c. Rent.
______ d. Depreciation.
______ e. Fuel cost at an airline.