Even though she had never instructed anyone on how to use the new software, Millicent accepted the responsibility of instructing Sherri because she knew she was capable of doing the job. Which aspect of a core self-evaluation does Millicent's belief represent?

self-efficacy

Explanation:

"Self-efficacy" is a term used by psychologist and is defined as the ability of a person to do a perform a particular task. It is the confidence in oneself to perform or behave in a particular situation.

So when Millicent taught Sherri to use the new software because Millicent knew Sherri has the skill to learn and use the particular software. Millicent is very much confident of Sherri that she is capable to use the new software.

Thus Millicent's belief in Sherri represents her "self-efficacy".