After a $3 per-unit tax on seeing movies in theaters is imposed, attendance falls from 4,000 a week to 3,000 a week. The revenue from the tax is

A) less than $9,000 a week.
B) $9,000 a week.
C) between $9,000 a week and $12,000 a week.
D) some amount that cannot be calculated without more information.

B