Supply and demand in a competitive market are given respectively by q = 4p and q = 30 - 2p. If the production of the good imposes a negative externality that generates an external cost for the society of 3 euros per unit exchanged, what is the socially optimal quantity in this market?
(a) q = 20
(b) q = 5
(c) q = 7
(d) q = 16
With calculation please