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
True about cathode-anode circuit is: 
Select and explain. 
A. Step up transformer, B. Step down transformer, C. 1 and 2, D. None of the above
A: Step up transformer
Answer: A: Step up transformer 
Explanation: Cathode – anode circuit has a step-up transformer (SUP) because the voltage has to be stepped up from 220 V to 65,000 V.