What describes a perfectly inelastic supply curve?

A perfectly inelastic supply curve indicates that the quantity supplied of a good remains constant, regardless of fluctuations in price. This situation means that suppliers cannot adjust the quantity they provide to the market, no matter how much the price changes. For instance, a unique artwork or a limited edition collectible would have a perfectly inelastic supply because the quantity available is fixed and cannot be increased or decreased based on price variations.

The other options represent different supply scenarios. Some describe cases where quantity supplied is responsive to price changes, which is not applicable to a perfectly inelastic supply. In contrast, the correct answer captures the core characteristic of this economic phenomenon, illustrating the lack of responsiveness from suppliers to price changes.