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
Which of the following tests is the least useful in endodontic diagnosis of children? 
Select and explain. 
A. Percussion, B. Palpation, C. Electric pulp test, D. Cold test
C: Electric pulp test
Answer: C: Electric pulp test 
Explanation: Electric pulp testL Until apical closure occurs, teeth do not respond normally to electric pulp testing. In addition, a traumatic injury may temporarily alter the conduction capability of nerve endings and/or sensory receptors in the pulp. A patient with a vital pulp may not experience any sensation right after trauma.