Practice question

Answer: C) Threshold once crossed produces fixed amplitude. For Action potential, once you lock onto the key mechanism or definition, Threshold once crossed produces fixed amplitude is the clear fit. If you restate the concept in your own words, cause and effect line up with Threshold once crossed produces fixed amplitude — that is the mechanism or reason the stem is pointing to. So Threshold once crossed produces fixed amplitude 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.