Assertion : Foetal disorders can be diagnosed by chorionic villi sampling.
Reason : Karyotyping can be done for mitotically dividing cells of chorionic villi.

If both assertion and reason are true and reason is the correct explanation of assertion.

If both assertion and reason are true but reason is not the correct explanation of assertion

If assertion is true but reason is false

If both assertion and reason are false

Solution

If both assertion and reason are true and reason is the correct explanation of assertion.

During early pregnancy, foetal disorders can be diagnosed using chorionic villi sampling. In this technique the physician inserts a narrow, flexible tube through the mother's vagina and cervix into the uterus (guided by ultrasound) and withdraws a small amount of foetal tissue (chorionic villi) from the placenta. Because the cells ofthe chorionic villi are undergoing rapid mitosis, these cells can be used for karyotyping.