Which of the following describes a logic bomb?

A logic bomb is specifically designed to execute a malicious action when certain conditions are met, such as a specific date or a triggering event, like the deletion of a particular file. This functionality makes option B the correct choice, as it captures the essence of a logic bomb's behavior: it remains dormant until activated, thus allowing it to carry out its harmful intentions at a precise moment or event.

The other options describe different types of malicious software or behaviors. For instance, the first choice refers to a trojan horse, which masquerades as a legitimate application to deceive users, while the third option describes a worm, which is designed to replicate itself and spread without causing damage but can still lead to other issues. The fourth choice aligns more with the definition of adware or ransomware, both of which may not operate on the triggering event principle characteristic of logic bombs. Therefore, focusing on the aspect of execution based on specific conditions makes option B the clear definition of a logic bomb.