Which one of the following is tested by the technique of amniocentesis

The correct option is chromosomal abnormalities in foetus.

Amniocentesis is a medical procedure used primarily for prenatal diagnosis. During this procedure, a small amount of amniotic fluid, which surrounds the developing fetus, is extracted from the amnion using a needle inserted through the abdomen. This amniotic fluid contains fetal cells (mainly skin cells) that have been shed by the developing baby.

The primary and most common clinical application of amniocentesis is to perform a karyotype analysis on these cultured fetal cells. Karyotyping allows doctors to examine the number and structure of the chromosomes to detect chromosomal abnormalities. Examples of conditions diagnosed this way include Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13), as well as sex chromosome abnormalities like Turner syndrome or Klinefelter syndrome.