Step 1: Understanding the Concept:
This is a knowledge-based question asking to identify the psychologist who developed the theory of cognitive dissonance.
Step 2: Detailed Explanation:
(C) Leon Festinger: In 1957, social psychologist Leon Festinger proposed the theory of cognitive dissonance. The theory states that individuals experience psychological discomfort (dissonance) when they hold two or more conflicting beliefs, ideas, or values, or when their beliefs are inconsistent with their actions. To reduce this discomfort, people are motivated to change their attitudes, beliefs, or behaviors.
(A) Fritz Heider is known for Balance Theory and Attribution Theory.
(B) Daniel Katz is known for the functionalist theory of attitudes.
Step 3: Final Answer:
The theory of Cognitive Dissonance was propounded by Leon Festinger.