<prompt> A 26-year-old pregnant woman has been detected to have a diastolic murmur in mitral area. Echocardiography reveals mitral valve orifice to be 0.8 cm2. The cause of her murmur isMild mitral stenosisSevere mitral stenosisFunctional murmurTransmitted murmur from the congenital hea disease of the foetus  <response>: Severe mitral stenosis 