Final answer:
Senator McEwan's supporters displaying unwavering trust in her integrity despite significant evidence of corruption is an example of d)belief perseverance, a concept closely related to motivated reasoning.
Step-by-step explanation:
The reaction of Senator McEwan's supporters, despite evidence of her guilt, best illustrates belief perseverance. This is a psychological phenomenon where individuals hold on to their beliefs even when confronted with overwhelming evidence to the contrary. Such behavior can be framed within the context of motivated reasoning, where people prioritize information that supports their pre-existing beliefs and attitudes and discount information that contradicts them. The loyalty McEwan's supporters demonstrate is similar to the phenomena observed in historical events, such as McCarthyism, where unsubstantiated accusations were accepted without question by many due to existing biases and political polarization.