Why Can't Your Immune System Fight Off the Toxins in Most

Why can't your immune system fight off the toxins in most venoms?

A) It probably could if it had time to, but the toxins act too quickly.
B) Your immune has never seen venom before unless you've been bitten before, so there are no memory cells to get to work.
C) The venom does not have antigens like normal pathogenic cells so it is invisible to the immune system.
D) Because a toxin isn't a cell, B cells and T cells don't recognize it as an invader.
E) Toxins are generally from reptiles and because we're mammals, our immune systems simply don't know what to make of a reptile product.