A is the best answer because class titles are capitalized only if they are being referred to as the course titles or contain proper nouns. "English" is always capitalized regardless of whether it's a class name, but "math," "social studies," and "marine biology" should always be lowercase unless those were being used as the class names.

• In B, the only thing wrong is that "Chemistry" should be lowercase. They're just general chemistry classes, whereas "English Honors I" and "History of Ancient People" can stay capitalized.
• In C, the classes named are just general, so they shouldn't be capitalized.
• In D, "math class" needs to be lowercase, though if it had just been "on his way to Math," the capital would be needed since it is talking about the name of the class.