Consider the Following Statements When Answering This Question I

Multiple Choice

Consider the following statements when answering this question I. If a firm employs only one variable factor of production, labor, and the marginal product of labor is constant, then the marginal costs of production are constant too.
II) If a firm employs only one variable factor of production, labor, and the marginal product of labor is constant, then short-run average total costs cannot rise as output rises.

A) I is true, and II is false.
B) I is false, and II is true.
C) I and II are both true.
D) I and II are both false.