A. Economies of scale
B. Money cost
C. Opportunity cost
D. Cost functions
Correct Answer: Option A
A. Economies of scale
Explanation
Economies of scale which is also known as scale of production set the size of plant, the number of plants installed and the technique of product. In the short-run, there is no time for the plant to expand while in the long-run, there is enough time for the firm to expand its size of plant which makes the AC α MC shape flatter.