<prompt> Congenital anomalies are most severe in:Rubella infectionMumpsCMVToxoplasma  <response>: Ans. is a, i.e. Rubella infectionRef. Williams Obs. 23e, p 1214Rubella is one of the most teratogenic agents known. Ref. Williams Obs. 23e, p 1214Rubella causes a number of serious defects in fetus. These defects may occur singly or in combination called Congenital rubella syndrome. 