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
Patient's cross infection with bite block of orthopantamograph machine is prevented by 
Select and explain. 
A. Cover with autoclaved cloth with each use, B. Using disposable bite blocks, C. Clean with 5.25% sodium hypochlorite in each patient, D. Cover with impervious barrier
B: Using disposable bite blocks
Answer: B: Using disposable bite blocks 
Explanation: Panoramic  and  cephalometric  equipment  should  receive  the same maintenance for decontamination and disinfection as other equipment. Panoramic bite-blocks, chin rest, and patient handgrips should be cleaned with detergent-iodine disinfectant and covered with a plastic bag. Disposable bite-blocks may be used. The head-positioning guides, control panel, and exposure switch should be carefully  wiped  with  a  paper  towel  that  is  well  moistened  with disinfectant.
Note: disposable bite-blocks are the preferred method, although they may not be cost effective.
Oral radiology ; White and Pharaoh 7th edition page no: 256