Final answer:
The italicized word 'French' in the sentence should be capitalized because it is a proper noun, which represents a specific language. This applies to all language names, which are always capitalized in English. The correct answer is option A.
Step-by-step explanation:
When it comes to capitalization of language names in a sentence, such as 'French' in the example 'Her favorite classes in school are science and French,' it is important to apply the rules of mechanics in terms of capital letters.
Language names are proper nouns and according to the English language mechanics, proper nouns and proper adjectives should always be capitalized. Therefore, the italicized word in the sentence should start with a capital letter, making the correct choice 'A. Yes'. Other common nouns, such as 'science' in this case, do not require capitalization unless they are at the beginning of a sentence or part of a title.