Kail (1991) Reported Increases in Processing Speed Between the Ages

Kail (1991) reported increases in processing speed between the ages of 6 to 12 for both motor and cognitive tasks. He demonstrated these increases in both the United States and Korea. Which one of the following statements concerning increases in information-processing skills is supported by Kail's findings?

A) Most of cognitive development can be explained by increases in long-term memory.
B) Processing efficiency increases are the basis for cognitive development.
C) Experience is not necessary for age-related increases in memory.
D) There is a limited relationship between memory increases and cognitive development.