Which phrase follows the rules of capitalization?

The choice "Professor Hopping" correctly follows the rules of capitalization because it includes a title that precedes a proper noun. In English grammar, titles referring to specific individuals, such as "Professor," are capitalized when they are used directly before a person's name. "Hopping" is a proper noun in this context, and it's customary to capitalize both the title and the individual's name.

In contrast, "Thanksgiving day" should be "Thanksgiving Day," as the holiday name is considered a proper noun and requires capitalization of both words. "uncle Larry" is incorrect because "uncle" is a common noun and should be capitalized only if used as part of a direct address or when it forms part of a proper noun (like "Uncle Larry"). Lastly, "Northern Canada" could be considered correct, as both words could be capitalized, but geographical references frequently follow specific styling rules that might allow for variations depending on the context. However, in this case, the clear and unambiguous example is "Professor Hopping," which adheres strictly to capitalization guidelines.