Consider the Following Production and Cost Schedule for a Firm

Multiple Choice

Consider the following production and cost schedule for a firm.The first column shows the number of units of a variable factor of production employed by the firm.
TABLE 13-1
-Refer to Table 13-1.Diminishing marginal returns are present for which units of the factor of production?

A) 10th unit only
B) 11th unit only
C) 12th unit only
D) 13th unit only
E) all units shown in the table