This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Physiology
What is the best stimulus for release of vasopressin 
Select and explain. 
A. Hypotonicity of extracellular fluid, B. Hypeension, C. Hypotension, D. Hypo-osmolality of extracellular fluid
C: Hypotension
Answer: C: Hypotension 
Explanation: Best / most impoant stimulus for ADH - Hypeonicity Next - hypotension Water deficit | |extracellular osmolarity |Osmoreceptors | ADH secretion (posterior pituitary) | |Plasma ADH | H2O permeability in |distal tubules. Collecting ducts | |H2O reabsorption | |H2O excreted 1. | Osmolality / tonicity 2. Aerial baroreceptor reflex - |aerial pressure - | ADH 3. Cardiopulmonary reflexes - | blood volume |ADH release |ADH release | plasma osmolality |plasma osmolality |blood volume |blood volume |blood pressure | blood pressure Nausea Hypoxia Drugs: Morphine Nicotine Cyclophosphamide Drugs: Alcohol Clonidine Haloperidol