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: Radiology
[{'content': 'Which of the following radiopharmaceutical is used in Imaging of Reticulo endothelial system \nSelect and explain. \nA. Tc-99m Red blood cells, B. Tc-99m Pyrophosphate, C. Tc-99m Sulfur Colloid, D. Tc-99m Teboroxime', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Tc-99m Sulfur Colloid -Imaging of RES, Gastric emptying, GI bleeds.', 'role': 'assistant'}]