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 is
Severe mitral stenosis
Mild mitral stenosis
Severe mitral stenosis
Functional murmur
Transmitted murmur from the congenital hea disease of the foetus