单选题 Which of the following statements most accurately describes the relationship between marginal product (MP) and average product (AP) of labor in the short run? As the quantity of output increases:

• A. AP is always less than MP.
• B. initially, AP＜MP, then AP=MP, then AP＞MP.
• C. initially, AP＞MP, then AP=MP, then AP＜MP.