<prompt> Normal size but non functioning uterus is usually associated with:Stenosis of the external osUterine synechiaePartial agenesis of the vaginaComplete absence of vagina  <response>: Lets have a look at each option:Option a: Stenosis of external os would result in hematometra, i.e. uterus would be large and non functioning hence ruled out.Option c: Partial agenesis of vagina In parital agenesis of vagina a segment of vagina may be atretic in the upper-third. It is often associated with hypoplasia or even absence of cervix. Uterus may be normal and functioning or malformed.Option d: Complete absence of vagina is almost always associated with absence of uterus.Hence by exclusion our answer is b i.e. uterine synechiae Asherman syndromeIn Uterine syechiaethe uterus does not function normally due to presence of adhesions size of uterus is normal. 