Before you see a question on the AP Psychology exam, it is usually pretested on a group of college students taking an introductory course in psychology. This group of people are referred to as the

Standardization sample

Explanation:

Standardization sample is a group of individuals which is pretested of a given scenario or exposure prior to start of any research or study so that at the later stage of the research or study, the results obtained by exposing new sample to the same scenario or exposure can be compared with the results obtained for standardized  sample.

the answer to your question is,

d. when a child was born.

-mabel < 3

answer; the cats meowing will temporarily increase, but then it will decrease;