Among the options given, the one that accurately represents a general observation about preschool children in the context of psychological testing is:
a) Their fatigue increases as testing time increases.
Preschool children, due to their young age and developmental stage, generally have shorter attention spans and become fatigued more quickly, particularly during tasks that require sustained attention or effort. Therefore, psychological tests for this age group are typically designed to be short and engaging to maintain their focus and minimize fatigue.