Use Figure: Negative Externality and Deadweight Loss II

Use Figure: Negative Externality and Deadweight Loss II. The figure shows the marginal benefit, marginal private cost, and marginal social cost that are associated with producing a good. The socially optimal price of the good is _____, and the socially optimal quantity is _____ units.
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Figure: Negative Externality and Deadweight Loss II

A) $18; 45
B) $18; 55
C) $16; 45
D) $16; 55