im annoyed at A being the answer because, sure it explains how fossilized shark skeletons are diff from other fossilized vertebraes (they're cartilage), but how can we just assume that the shark teeth are not cartilage? it doesn't really make clear the diff between shark teeth and shark skeleton for me, it only clears up fossilized shark skeleton vs others. am i allowed to just assume shark teeth are not cartilage based on the way A is written? i don't think that any of the other answer choices are any better than A, but I'm nervous to repeat the same issue I have with A on other questions.