Question

A perfectly inelastic demand curve is

•  A. horizontal.
•  B. a curved line along which the product of price and quantity is constant.
•  C. a downward sloping straight line with a slope equal to 1.
•  D. vertical.

Answer 1

The demand curve for a perfectly inelastic good is depicted as a vertical line in graphical presentations because the quantity demanded is the same at any price.

So, the correct answer is D.