Answer: Research suggests that during early and middle adulthood,
A. Crystallized intelligence increases and fluid intelligence decreases
Explanation: Crystallized intelligence is the intelligence that one gains over time through life; techniques such as reading comprehension, mathematics, vocabulary, etc. Fluid intelligence can be defined as the ability to think abstractly, reason, problem solving, and independent thinking. After adolescence, scientists have found that fluid intelligence decreases and crystallized intelligence increases throughout life.