Grammar question help...?

Joy and sorrow are two side of the same coin. Joy and sorry are two sides of the same coin. Which one is right? According to the website I was using for this: "Choice C [the first sentence above] agrees with the subject, but the noun side is singular although it is modified by two." "The verb... show more Joy and sorrow are two side of the same coin.
Joy and sorry are two sides of the same coin.

Which one is right?
According to the website I was using for this:
"Choice C [the first sentence above] agrees with the subject, but the noun side is singular although it is modified by two."
"The verb has to agree with the subject. Here the conjunction and joins two singular nouns; the subject is therefore plural. Choice D [the second sentence] uses correct subject-verb agreement."

I get what the site is trying to tell me, but I still don't think it's right...
Update: EDIT: Crap, I mean Choice C is the second one and Choice D is the first one.
5 answers 5