Figure: Traffic Lights in Plymouth

Multiple Choice

Figure: Traffic Lights in Plymouth
(Figure: Traffic Lights in Plymouth) Plymouth has 1,000 residents.The figure Traffic Lights in Plymouth shows the marginal social benefit and marginal cost of traffic lights in town.We know that each of the residents has the same individual marginal benefit per traffic light.If the government provides traffic lights, the socially efficient quantity is:

A) 0.
B) 4.
C) 8.
D) 12.