UGC-NET 2024 Question 91: Monopoly and price discrimination

Comprehension - Social cost of monopoly power (diagram). A demand/AR curve, MR curve and an upward-sloping MC curve are drawn. The competitive price-quantity is $(P_c, Q_c)$ where MC = AR, and the monopoly price-quantity is $(P_m, Q_m)$ where MR = MC ($P_m > P_c$, $Q_m < Q_c$). The area between $P_m$ and $P_c$ up to $Q_m$ is rectangle A; the upper triangle (to the AR curve) is B; the lower triangle (between AR and MC) is C.

Question: Find the consumer loss due to the move from the competitive to the monopoly price ($P_c$ to $P_m$):