Over the range of output where the slope of the short-run total cost curve becomes steeper:

Increasing returns to scale occurs when a firm's:

a. average costs of production increase as its output increases. b. average costs of production decrease as its output increases. c. average fixed costs increase as its output increases. d. marginal costs increase as its output increases.

The supply of workers in a particular occupation could be relatively large if:

A. training costs are low. B. job features are undesirable. C. there are few people with the required skills. D. there are artificial barriers to enter that profession.