Developmental psychologists have attempted to identify the effects of many specific childrearing practices on children's personality traits. The problem with this line of research, which was discussed in the textbook, is that:

A) parents who use physical punishment won't be honest with the researchers.
B) psychologists cannot agree on whether to use cross-sectional or longitudinal approaches.
C) it is difficult to recruit parents to serve as participants in this research.
D) parents are inconsistent from day to day and over the years.