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
An important clinical feature of a concussed tooth is: 
Select and explain. 
A. Tooth is markedly tender to percussion, B. Tooth is displaced from the socket, C. Evidence of haemorrhage at gingival margin, D. Clinically crown appears shorter
A: Tooth is markedly tender to percussion
Answer: A: Tooth is markedly tender to percussion 
Explanation: Concussion 

Tooth is not displaced.
Mobility is not present.
Tooth is tender to percussion because of edema and hemorrhage in the periodontal ligament.
Pulp may respond normal to testing.