The Following Figure Shows Revenue and Cost Curves of a Monopolist

The following figure shows revenue and cost curves of a monopolist. Figure 10.8
AR: Average revenue curve
MR: Marginal revenue curve
MC: Marginal cost curve
-According to Figure 10.8,the profit maximizing price of the monopolist is:

A) 0.
B) P_4.
C) P_3.
D) P_2.
E) P_1.