Constant Returns to Scale Indicate That a Firm Experiences

Constant returns to scale indicate that a firm experiences:

A) decreasing per-unit costs of production as the scale of output expands.
B) stable per-unit costs of production as the scale of output expands.
C) increasing per-unit costs of production as the scale of output expands.
D) increasing marginal product.
E) increasing short-run costs of production as output expands.