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': 'Velocity of X-ray is: \nSelect and explain. \nA. 1 lakh miles/sec, B. 2 lakh miles/sec, C. 3 lakh miles/sec, D. 0.5 lakh miles/sec', 'role': 'user'}, {'content': 'Answer: B \nExplanation: X-rays are electromagnetic radiations with following properties:\n\nVelocity = 3 x 108 m/sec or 2 lakh miles/sec\nThey cannot be focused, reflected or refracted.\nThey cast the shadow of the objects falling in their path.\nThey are affected by electric and magnetic field.\n\nRef: Karjodkar 3rd Ed, Pg-72', 'role': 'assistant'}]