<prompt> For normal mammography, X-ray tube with a nominal focal size of-mm is used?0.2-0.250.3-0.350.4-0.450.45-0.50  <response>: 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. 