Say a Public Good Is Provided to Two Consumers: John

Say a public good is provided to two consumers: John and Jill. John's willingness to pay for the good is P = 10 - Q, and Jill's is P = 20 - 2Q. The marginal cost to provide the good are 2Q. Assume the government must pay for providing this good by taxing Jill and John equally to raise the necessary revenue. When the optimal quantity of this good is provided, Jill's willingness to pay for the good is

A) 4.
B) 12.
C) 48.
D) 2.