Which of the following types of stock guarantees a dividend even when the issuing corporation does not earn a profit?

The type of stock that guarantees a dividend payment even when the issuing corporation does not earn a profit is known as protected preferred stock. This particular class of preferred stock comes with certain rights and assurances, one of which is the commitment to pay dividends before any dividends can be paid to common stockholders.

Protected preferred stock has features that provide security to investors, including cumulative dividend rights, which means that if a dividend is not paid in a given year (due to the corporation not earning a profit, for example), it must still be paid in the future before any distributions can be made to common shareholders. This preference for receiving dividends helps to mitigate the risk for investors during times when the company's profitability may be fluctuating.

In contrast, collateral preferred stock, capital stock, and common stock do not provide the same level of guarantee regarding dividend payments. Collateral preferred stock may come with specific asset backing, but does not guarantee dividends if the company does not generate profits. Capital stock typically refers to common shares, which are the last in line for dividends unless all preferred dividends have been satisfied. Common stockholder dividends are discretionary and depend entirely on the company's profitability and decisions made by the board of directors.