I would say it is B it. I'm not 100 percent on this one.
Does it have to be over a certain topic?
I think it’s A.
Hope this helps!!
I'm not quite sure how you want me to answer this but here...
'My three classes, biology, English, and reading are very hard but they are not as difficult as math.'
You do not capitalize classes unless it is a language or it as a number behind it (ex. Algebra 1.).
