Table 13-2 The Table Represents a Demand Curve Faced by a Firm

Table 13-2
The table represents a demand curve faced by a firm in a competitive market.

-Refer to Table 13-2.For a firm operating in a competitive market,the marginal revenue from selling the 3rd unit is

A) $12.
B) $4.
C) $3.
D) $1.25.