Which of the following statements describes a perfectly inelastic demand? A. The government is promoting generic drugs that are much cheaper. B. Walgreens does not find any change in the number of people buying chlorthalidone after a 7 percent rise in its price. C. I prefer taking the subway to work rather than driving because of high fuel prices. D. A large number of youngsters buy roses from Colombian rose-growers before Valentine's Day.

The correct answer is B. Walgreens does not find any change in the number of people buying chlorthalidone after a 7 percent rise in its price.<br /><br />In a perfectly inelastic demand scenario, the quantity demanded remains constant regardless of changes in price. This means that consumers are willing to pay any price for the product, and the demand does not change even if the price increases or decreases. In this case, the fact that Walgreens does not find any change in the number of people buying chlorthalidone after a 7 percent rise in its price indicates that the demand for the drug is perfectly inelastic.