When Psychologists Compare Separate Groups of 3­ Year­olds, 18­year­olds, and 40­year­olds

Multiple Choice

When psychologists compare separate groups of 3­ year­olds, 18­year­olds, and 40­year­olds on a vocabulary test, they are conducting a:

A) longitudinal study.
B) kinship study.
C) clinical study.
D) cross­sectional study.