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
Contrast used for MRI – 
Select and explain. 
A. Iodine, B. Gadolinium, C. Metvazamide, D. Pmnipaque
B: Gadolinium
Answer: B: Gadolinium 
Explanation: Gadolinium is the most commonly used MR contrast agent.