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: Surgery
One day after complete mouth extraction, blue black spots are seen on the neck of the patients. These spots indicate: 
Select and explain. 
A. Thrombocytopenic purpura, B. Postoperative ecchymosis, C. Impaired blood circulation, D. Cellulitis
B: Postoperative ecchymosis
Answer: B: Postoperative ecchymosis 
Explanation: None