Which of the following phrases follows the rules of capitalization?

The phrase "my cousin Michelle" follows the rules of capitalization because "Michelle" is a proper noun, referring to a specific person and therefore requires capitalization. The word "cousin" is a general term and does not need to be capitalized unless it is used as a title before a name, which it is not in this case.

In contrast, the other options contain improper capitalization. "uncle Elson" incorrectly capitalizes the name but not the title "uncle," which should be lowercase in this context. "your Mother" incorrectly capitalizes "Mother," which should only be capitalized if used as a title directly addressing someone (e.g., "Mother said"). "his Aunt" similarly misuses capitalization; "Aunt" does not need to be capitalized unless used in a similar context as a title before a name. Thus, "my cousin Michelle" adheres to capitalization rules by correctly capitalizing only the proper noun.