Four Stores Have a Problem with Theft and Security Is

Multiple Choice

Four stores have a problem with theft and security is a public good.Let S stand for the number of person-hours of security patrols per week.The marginal benefit of security patrols to each of the stores is given by the formula MB = 200 - 2S.Patrols cost $20 per hour.What is the socially efficient level of security?

A) 90 person-hours of patrols per week
B) 100 person-hours of patrols per week
C) 92.5 person-hours of patrols per week
D) 97.5 person-hours of patrols per week