Available options: a). prokaryotes. b). human cells. c). peachleaf willow. d). graptolites. e). barnacles. f). plant cells. g). eukaryotes. h). gastropod shells.

You are presented with the quiz "What lacks regions that do not code for proteins?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "introns are regions that do not code for proteins" and "prokaryotes lack introns, whereas eukaryotes contain introns". So, what's the best answer to the question?
Answer:
a).