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: Unknown
Wound contraction is primarily mediated by 
Select and explain. 
A. Smooth muscle cells., B. Macrophages., C. Fibroblasts., D. Myofibroblasts.
D: Myofibroblasts.
Answer: D: Myofibroblasts. 
Explanation: Myofibroblasts, cells with features intermediate between fibroblasts and smooth muscle cells, appear in the wound 2 to 3 days after injury. Their active contraction decreases the size of the defect.