This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Endo-cochlear potential is: 
Select and explain. 
A. +45 mV, B. --45mV, C. -60mV, D. +85 mV
D: +85 mV
Answer: D: +85 mV 
Explanation: Ans: D.+85 mV(Ref Ganong 25/e p204, 24/e p203; Guyton I 3/e p677)Endocochlear potential:Cells in stria vascularis have a high concentration of Na, K ATPase.Exists all time between endolymph & perilymph.Positivity inside scala media & negativity outside.This is called endocochlear potential.Generated by continual secretion of positive potassium ions into scala media by stria vascularis.Normal: +85 mV