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.

【正确答案】 B

【答案解析】[解析] 由图可知，当生产要素(劳动L)的投入数量低于OB时，AP＜MP；当生产要素(劳动L)的投入数量达到OB时，AP=MP；当生产要素(劳动L)的投入数量高于OB后，AP＞MP。因此，本题的正确选项为B。