This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
A patient present to emergency with pinpoint pupil, salivation, lacrimation, tremors and red tears. Plasma cholinesterase level was 30% of normal . Most probable diagnosis is 
Select and explain. 
A. Organophosphate poisoning, B. Datura poisoning, C. Opioid poisoning, D. Pontine haemorrhage
A: Organophosphate poisoning
Answer: A: Organophosphate poisoning 
Explanation: Refer katzung 12e p110 These are characteristic feature of anticholinesterase(organophosphorous and carbamates) poisoning features of organophosphate poisoning muscarinic symptoms: pinpoint pupil, salivation, lacrimation ,urination,defecation,gastrointestinal distress, vomiting, bronchospasm, bradycardia nicotinic symptoms: fasciculations and fibrillation of muscle, tachycardia and tachypnea CNS symptoms :Tremors, giddiness, ataxia and coma red tears: due to accumulation ofporphyrin in the lacrimal glands