What Is the Fundamental Insight Underlying the "Cognitive Walk Through

What is the fundamental insight underlying the "cognitive walk through" method of evaluation?

A) processes are the most important aspect of the user experience
B) the idea that users can sometimes be left out of the evaluation
C) the idea that users earn by exploring an interface text should be legible and distinguishable from its background under different lighting conditions
D) the idea that experts need to work hand in hand with useers to develop an optimal user experience