Final answer:
The scenario described by the student, where vivid memories of an older relative endure over time without conscious recall, raises issues with the decay theory of forgetting, which suggests that memories fade over time when not used.
Step-by-step explanation:
The student's question relates to the concept of forgetting and which theory might be problematic based on the scenario provided. In this case, the student has vivid memories of an older relative after a long period without thinking about them, suggesting that memory can persist despite a lack of conscious recall. This poses a problem for the decay theory of forgetting, which posits that memories fade or erode over time due to non-use. This theory would predict that the lack of active recall would lead to memories fading away, which contrasts with the student's experience of vividly remembering the relative.
The persistence of vivid, long-term memories indicates that information does not simply vanish due to time but may be related to how it is encoded, the relevance to the individual (self-reference effect), and the strength of the initial memory trace. Other theories, such as interference (proactive and retroactive), suggest that forgetting occurs due to new memory inhibiting the retrieval of old memory or vice versa, which is also not directly supported by this scenario. Thus, the final answer to this student's question is a. Decay.