Match each of the following costs with its appropriate definition:
_____ 1. Fixed cost per unit
_____ 2. Fixed costs in total
_____ 3. Variable cost per unit
_____ 4. Variable costs in total
_____ 5. Step costs
A. Vary directly and proportionally with changes in volume.
B. Varies inversely with the activity level.
C. Remains constant in the short run, regardless of changes in activity.
D. Constant over small ranges of output, but increases as levels of activity increase.