Tim Horton's coffee cups litter downtown Calgary, creating a negative externality. Tim Horton's ...

Tim Horton's coffee cups litter downtown Calgary, creating a negative externality. Tim Horton's could correct for this externality by
A) increasing the price of coffee by an amount equal to the marginal external cost of collecting this litter.
B) serving coffee without cups.
C) lowering the price of coffee so that smart consumers will buy more.
D) lowering the price of coffee by an amount equal to the marginal external benefit of collecting the litter.
E) raising the price of coffee by an amount that is greater than the marginal external cost of collecting this litter.