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: Dental
A cold test best localizes 
Select and explain. 
A. Pain of pulpal   origin., B. Periodontal pain., C. Pulp necrosis., D. Referred pain.
A: Pain of pulpal   origin.
Answer: A: Pain of pulpal   origin. 
Explanation: Hyperalgesia  is  manifested  in endodontic pain patients when noxious stimuli (e.g., refrigerant  sprays  or  carbon  dioxide  snow  used  in  the  cold  test) produce much more pain than they would in teeth with normal pulp tissues. Spontaneous pain involves episodes of pain that seem to  be  unprovoked.  All these changes can be partly Explained by sensitization of peripheral nerve endings in the pulp.
Cohen's Pathway of the Pulp ed:11th Pg551