Final answer:
An assignment of an earnings rating is required only for institutions that have total trust assets of more than $50 million with a composite rating of 3, 4, or 5.
Step-by-step explanation:
An assignment of an earnings rating is required only for institutions that, at the time of the examination, have total trust assets of:
a. More than $50 million with a composite rating of 3, 4, or 5.
b. All institutions regardless of assets under management.
c. $100 million and less.
d. More than $100 million.
Based on the given information, a trust institution needs to have total assets of more than $50 million and a composite rating of 3, 4, or 5 in order to require an earnings rating.
Therefore, option a is the correct answer.