Practice question

Answer: B) Na+. For Action potential, once you lock onto the key mechanism or definition, Na+ is the clear fit. If you restate the concept in your own words, cause and effect line up with Na+ — that is the mechanism or reason the stem is pointing to. So Na+ is the clean, accurate selection. If a similar stem appears later, start from the same core fact and you will land on the same kind of answer. In class notes, highlight this same phrase next to the related diagram so the wording and the picture reinforce each other. When you practise, cover the choices first, write Na+ from memory, then reveal the letter — that habit builds real recall for Action potential.