Practice question

-90 mV (C) is the right choice. This sits at the heart of Cardiovascular System: Heart: the wording points straight to what is happening in the tissue or organ system. A useful study habit is to ask what the structure or process is for: -90 mV is the option that correctly names the structure, process, or principle asked for in Cardiovascular System: Heart. That reasoning supports -90 mV. One solid sentence about why this works is enough for recall — you do not need a long essay for every MCQ. When you practise, cover the choices first, write -90 mV from memory, then reveal the letter — that habit builds real recall for Cardiovascular System: Heart.