The correct option is C Amniocentesis
A congenital disorder is the abnormalities or defects that occur at the time of before birth. It comes from parents. Thus, the study of physical abnormalities of the embryo is called as a congenital disorder and it is diagnosed by amniocentesis.
The study of abnormalities by taking out the amniotic fluid of an embryo is called amniocentesis. In this technique, a small amount of amniotic fluid, which contains foetal tissues, is sampled from the amniotic sac surrounding a developing foetus, and the foetal DNA is examined for genetic abnormalities. ∙ Genetic disorders like Down syndrome, haemophilia, sickle-cell anaemia, etc., determined by amniocentesis.
Hence, the correct answer is option “B”- Amniocentesis.