To Internalize a Positive Externality

To internalize a positive externality:

A) ​the consumers of a good could receive a subsidy equal to the external benefit resulting from the production or consumption of the good.
B) ​a producer's costs could be increased by an amount equal to the external benefit resulting from the production of the good.
C) ​consumers of the good could pay a tax equal to the external benefit resulting from the production or consumption of the good.
D) ​None of the above are correct.