Thank you guys! You all have been a big help! I have some direction! :) If you think of anything else that will help shore up my basic understanding of arguments... please let me know!
Flash cards are definitely the way to go if you're trying to memorise them. Having the valid and invalid forms on index cards, and drilling them together helped me, that way I had to actually think about it rather than just look at it.
I have a little note pack of things I need to remember... biconditionals, valid/invalid argument forms! I review it every morning while I blow dry my hair! (multittasking FTW)
OP review the Valid Argument Form 4 in the "Some and Most Relationships." The inference (B) in this Q is very clear. (D) is reversal of the first sentence.