What are you referring to as "bags"? When I read that, it made me think of illicit drugs. Most products that come in bags are named explicitly in most contexts, and bags themselves (e.g. trash bags and sandwich bags) are sold in multipacks; you don't just buy one at a time.
In any case, yes, those are all fine grammatically. But "A" and "B" refer to your willingness to do it, and "C" and "D" refer to your happiness about the fact that you are able to do it.