So I picked A, which I now understand is wrong because I guess B is a better answer.
Is B correct because the mouse antibody (a protein) would be considered an antigen by the human immune system and thus lead to an attack? Would it essentially be the same as putting a foreign material in our body which is susceptible to attack? Or is there a bigger explanation?
yes. A doesn't really do any explaining that is grounded in biology or anything explaining at all. B is pretty self evident. it's the same reason why we don't use pig insulin for treating diabetes anymore, in addition to cost. You might want to skim through this:
