Final answer:
The highest score for crystallized intelligence is expected at age 45, as this type of intelligence remains steady or may even improve into middle adulthood, unlike fluid intelligence which can decline later in life.
Step-by-step explanation:
If you are tested longitudinally for skills involving the use of crystallized intelligence, you would expect to have the highest score at age 45 (option b). Crystallized intelligence refers to the knowledge and skills that one acquires through experience and education, and it typically improves or remains stable well into middle adulthood. This is in contrast to fluid intelligence, which refers to the ability to process information, reason, and remember; fluid intelligence may decline in later adulthood.
Research, such as that by Bayley & Oden (1955), has shown that adults maintain stable scores or show improvements in tests of crystallized intelligence up until their mid-30s to mid-50s. After that range, a decline is more likely to occur in fluid intelligence, not crystallized intelligence. To maintain cognitive health, engaging in mental and physical activities is beneficial, as it can delay cognitive decline and reduce the incidence of cognitive impairments.