This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid & Electrolyte, Subject name: Medicine
Which ion channel is affected in hypokalemic periodic paralysis? 
Select and explain. 
A. K+, B. Na+, C. Cl-, D. Ca2+
D: Ca2+
Answer: D: Ca2+ 
Explanation: Ans. (d) Ca2+Ref : Harrison's Internal medicine 18/e, chapter 387, table 387-10