Few research studies on cognitive development focus on adulthood that is ______.

A) emerging
B) young
C) middle
D) old

Most research studies on cognitive development in adulthood focus on the middle-age period, which is roughly between the ages of 40 and 60. This period is considered important because it marks a transition between early adulthood and old age, and is associated with various changes in cognitive abilities, such as those related to memory, attention, and problem-solving. While there is some research on cognitive development in emerging adulthood (ages 18-25), and in old age (65 and above), the majority of studies on cognitive development in adulthood focus on the middle-age period.