Which of the following is a circumstance that can void guaranteed salaries?

The correct choice is substance abuse, as it can lead to the voiding of guaranteed salaries in the context of NFL contracts. Generally, when a player fails a drug test or violates the league's substance abuse policy, the team has the right to terminate the player's contract, which includes any guaranteed salary provisions. This serves as a significant deterrent against substance use and reinforces the league's commitment to maintaining player health and safety.

Guarantees in player contracts are designed to provide some financial security to players, but they come with conditions. Violating the league’s substance abuse policy is considered a serious offense that undermines a player's commitment to their professional responsibilities, hence the potential for contracts to be voided.

Other circumstances mentioned, such as injury during a game and failure to meet performance goals, do not typically lead to the voiding of guaranteed salaries. Injuries are often covered under contract protections that allow players to still receive their salaries while they are unable to play. Similarly, while performance goals may affect bonuses and incentives, they do not usually impact the guaranteed base salary. Refusal to attend training camp can lead to fines or disciplinary actions, but it does not automatically void guaranteed salary clauses.