A Primary Challenge of the Technique Called Introspection That Was

A primary challenge of the technique called introspection that was favored by structuralists is that it cannot ________.

A) identify what is going on within any one person's consciousness
B) distinguish any differences between men and women, which limits its usefulness
C) be conducted individually; many people had to be studied at the same time to achieve valid results
D) be used to study children, animals, or more complex mental disorders