This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
This patient's serum was found to be discolored four hours following a surgical procedure. What is the most likely cause? 
Select and explain. 
A. Fluorescent dye, B. Methemoglobinemia, C. Propofol, D. Pseudomonal sepsis
A: Fluorescent dye
Answer: A: Fluorescent dye 
Explanation: Answer A. Fluorescent dyeThe patient had undergone intraoperative angiography with a fluorescent dye and a Wood's lamp was used to evaluate mesenteric-vessel viability.