In the Short Run, Total Cost Increases

In the short run, total cost increases:

A) at a constant rate at all levels of output because the amount and productivity of fixed factors never changes.
B) rapidly at first because many variable factors are needed to increase output when they are combined with a given amount of fixed factors.
C) slowly at first because a few variable factors can increase output significantly when they are combined with a given amount of fixed factors.
D) none of the above.