Longitudinal research is more accurate than cross-sectional research when it comes to measuring development of intelligence over the decades, but there are three drawbacks tothis research design. Which of the following is NOT one of the drawbacks?

A)an inability to determine continuity and discontinuity of intellectual development
B)unusual events affecting each cohort, and more mundane changes making the data on one cohort less relevant to later cohorts
C)the loss of some participants across time, which could skew the results
D)repeated testing provides practice, which could improve scores