Answer: d. total cost and variable cost
A variable cost<span> is a company expense that changes in parallel with production output. They rise as production increases.</span>
Total cost<span> refers to the total company expense incurred in producing a particular level of output. Same with the variable cost, it increases as production increases.</span>
Purchases = Sales units + Closing inventory - Beginning Inventory
= 7,400 + (2,400 * 120%) - 2,400
= 7,800 units