This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Which ion causes repolarization? 
Select and explain. 
A. Magnesium, B. Calcium, C. Potassium, D. Sodium
C: Potassium
Answer: C: Potassium 
Explanation: When potassium goes from inside to outside it causes rapid repolarization. (REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, PAGE NO - 26)