To Examine Whether or Not Children's Cognitive Development Occurs in Stages

To examine whether or not children's cognitive development occurs in stages, Professor Blue observes four different groups of children. Each child's performance on cognitive tasks is observed two or more times over a period of two years. Which of the following groups is MOST likely to lead Professor Blue to the conclusion that development occurs continuously?

A) Group A, whose performance on a single task is observed twice each year
B) Group B, whose performance on multiple tasks is observed twice each year
C) Group C, whose performance on a single task is observed every week
D) Group D, whose performance on multiple tasks is observed every week