Endolymph is rich in which ion?
K+ (C) is the right choice. This sits at the heart of Sensory System Ear Physiology: 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: K+ is the option that correctly names the structure, process, or principle asked for in Sensory System Ear Physiology. That reasoning supports K+. 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 K+ from memory, then reveal the letter — that habit builds real recall for Sensory System Ear Physiology.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.