Final answer:
Tom's difficulty in retrieving study material during exams without being able to smoke is an example of context-dependent memory, where environmental cues help trigger memories learned in that context.
Step-by-step explanation:
Tom may find it more difficult to retrieve study material during his exams if he is not in the same context as when he was studying, which is known as context-dependent memory. This concept suggests that we are better at remembering information when we are in the same environment in which we learned it, as cues from our surroundings can trigger the memories. Therefore, since Tom smokes while studying in his apartment and cannot smoke during his exams, the lack of this familiar context may make retrieval of the material more challenging.