One advantage of the sequential design is that

One advantage of the sequential design is that
A)   researchers can find out whether cohort effects are operating by comparing participants of the same age who were born in different years.
B)   it permits cause-and-effect inferences by studying groups of people differing in age at the same point in time.
C)   it presents participants with a novel task and follows their mastery over a series of closely spaced sessions.
D)   it is especially useful for studying the strategies children use to acquire new knowledge in reading and science.