Final answer:
At the base of the Pyramid of Information-Processing Domains in Cognitive Information Processing theory, 'Problem Solving' represents the fundamental skills necessary for higher-level cognitive functions.
Step-by-step explanation:
In the Pyramid of Information-Processing Domains within Cognitive Information Processing (CIP) theory, the base of the pyramid, representing fundamental skills, is 'C) Problem Solving.' This level represents the essential cognitive processes used to identify and solve problems, which serve as the foundation for higher-level cognitive functions and skills that are built upon them. Problem-solving abilities are critical as they can be applied to new and varied situations, which is much more useful in a variety of contexts than simply memorizing facts.