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
False regarding protective co-contraction muscle splinting: 
Select and explain. 
A. Reduced mouth opening due to infection, B. Protective co-contraction is not a pathologic condition, C. There is no pain reported when the muscle is at rest, but use of the muscle will typically result in increased pain., D. Altered sensory input or pain, antagonistic muscle groups fire during movement in an attempt to protect the injured part.
A: Reduced mouth opening due to infection
Answer: A: Reduced mouth opening due to infection 
Explanation: Protective Co-contraction (Muscle Splinting) 
Protective co-contraction is the initial response of a muscle to altered sensory or proprioceptive input or injury (or threat of injury). This response has also been called protective muscle splinting or coactivation. It is not associated with reduced mouth opening due to infection.