The brain slows down in late adulthood, with variation in abilities and vocabulary likely to stay intact while processing speed declines. Which phrase best captures this?

• A. Wear and tear
• B. Genetic clock
• C. Changes in brain functioning
• D. Hayflick limit

Answer: (C)

Aging brings changes in brain functioning that affect how quickly we process information, while some well-practiced knowledge like vocabulary can remain stable. This idea fits the observed pattern: processing speed tends to decline with age due to changes in neural processing, white matter, and brain networks, but crystallized abilities such as vocabulary often stay relatively intact because they’re built from accumulated experience and knowledge over many years.

The phrase that best captures this is changes in brain functioning, because it describes the overall, biology-based shifts in how the brain works that produce slower processing while allowing vocabulary to persist. The other options point to different ideas that don’t fit the cognitive aging pattern as well: wear and tear suggests general damage from use, genetic clock implies a fixed, predetermined timing of aging at a cellular level without focusing on cognitive change, and the Hayflick limit is about how many times cells can divide, not about how aging affects brain function or cognition.