This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Radiology
For normal mammography, X-ray tube with a nominal focal size of-mm is used? 
Select and explain. 
A. 0.2-0.25, B. 0.3-0.35, C. 0.4-0.45, D. 0.45-0.50
B: 0.3-0.35
Answer: B: 0.3-0.35 
Explanation: Ans BIn general smaller the focal spot sharper the image Routinely focal spot size 0.3x0.3mm while magnification technique small focus of 0.1x0.1mm is used.