Which word means appropriate, suitable, or relevant?

The word "apposite" means appropriate, suitable, or relevant, making it the correct choice in this context. It is often used to describe remarks, comments, or actions that are particularly timely and fitting for a given situation. In various contexts, when something is described as apposite, it signifies that it aligns well with the subject at hand and enhances understanding or engagement with that subject.

In contrast, disingenuous refers to a lack of sincerity; jeer denotes mocking or scoffing at someone, which is entirely unrelated; and replete suggests a state of being fully supplied or filled, which does not convey appropriateness or relevance. Each of these words, therefore, lacks the specific connotation of suitability that "apposite" embodies.