Throwing the towel in.

Now the big question I am having is when do i throw the towel in. I was trying for an A in American lit, but yesterday i lost it. i failed a test and is brought me down to a B-. and i have other things i really need to focus on. like US history. I am going to get an A on that final i just need to study real hard for it. and i am going to do that, so do i be done with Am. Lit, when is it time to throw in the towel and take the B? i just don't know. i know. It was bring my GPA down, but i don't want to over do myself and end up with two B. i am praying to god, that he will help me. that is all about i have left. SO i am just going to keep going along and keep studying its the only thing I can do.