Answer: (D) hardening of the arteries.
Explanation:
Changes in memory are normal in middle-aged adults, but contrary to what people usually believe, even though some cognitive faculties become frailer with age, others may become better.
The most dramatic changes happen in the way we encode and retrieve information. Interference, such as distractions and stress, may block encoding, slowing the process of retrieval. But the hardening of the arteries is not a factor on memory changes.