Answer:
The correct answer is c) is not useful to psychologists who study normal memory.
Step-by-step explanation:
Since both researches study extraordinary cases - one related to poor functioning of the memory due to physical conditions and the other related to an uncommonly acute performance, they are useless to the understanding of how memory works in normal conditions. Thus, option A would be incorrect.
Option B confuses memory with consciousness, which are very different things and option D is a false conclusion.