Explanation

Pronuclear Transfer (PNT) is an advanced form of Mitochondrial Replacement Therapy (MRT) used during in-vitro fertilization (IVF):

– It is engineered specifically to prevent mothers carrying deleterious mutations in their mitochondrial DNA (mtDNA) from transmitting fatal mitochondrial diseases to their children.
– In this laboratory technique, the mother’s egg is fertilized with the father’s sperm to form a zygote. Before nuclear fusion occurs, both parental pronuclei (containing over 99.9% of the genetic code) are extracted and transplanted into an enucleated donor zygote containing healthy, functional donor mitochondria.
– The resulting embryo develops free of maternal mitochondrial defects.

Therefore, pronuclear transfer is deployed for the prevention of mitochondrial diseases in offspring — Option D.