Suppose That Dent Carr's Long-Run Total Cost of Repairing S

Suppose that Dent Carr's long-run total cost of repairing s cars per week is c(s) = 2s² + 50. If the price he receives for repairing a car is $8, then in the long run, how many cars will he fix per week if he maximize profits?

A) 2
B) 0
C) 4
D) 3
E) 6