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
[{'content': 'Hot water bottle relieves pain of abdominal spasm by: \nSelect and explain. \nA. Stimulation of adrenergic fibers, B. Stimulation of cholinergic fibers, C. Inhibition of cold receptors, D. Inhibition of heat receptors', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hot water bottle relieves abdominal pain through stimulation of adrenergically activated A delta and C fibres, there by blocking pain impulses transmitted through visceral C fibers. Ref: The Journey to Pain Relief : A Hands-On Guide to Breakthroughs in Pain Treatment By Phyllis Berger, Page 76; The Neurobiology of Pain : Symposium of the Nohern Neurobiology Group, Page 232; The Human Nervous System : Structure and Function By Charles Robe Noback, Page 171.', 'role': 'assistant'}]