-Refer to the Above Figure $\mathrm { Q } _ { 1 }$

-Refer to the above figure.The market equilibrium quantity is $\mathrm { Q } _ { 1 }$ .Point $\mathrm { Q } _ { 2 }$
Represents the optimal amount of production.The government can achieve the optimal outcome by

A) setting the price at $\mathrm { P } _ { 3 }$ .
B) providing a per-unit subsidy to consumers equal to $\mathrm { P } _ { 3 }$ -
$P _ { 1 }$ .
C) providing a per-unit subsidy to consumers equal to $P _ { 2 }$ -
$P _ { 1 }$ .
D) establishing a tax equal to $P _ { 2 }$ -
$P _ { 1 }$ per unit of the good sold.