For the following alternatives, please argue which is true, false or uncertain according to the following statement:

"If a certain activity that is not regulated produces a negative externality in production, then it can be inferred that":

(a) the equilibrium price is higher than the socially optimal price.

(b) the equilibrium quantity is greater than the socially optimal quantity

(c) the supply of the activity is less than the socially optimal supply

(d) it is necessary to subsidise the activity