(a) Fertilisation of egg in vitro by the donor sperm

(b) Genetic modification of sperm-producing cells

(c) Development of stem cells into functional embryos

(d) Prevention of mitochondrial diseases in offspring

Ans: d

Explanation:

Mitochondrial DNA (mtDNA) mutations are a common cause of genetic disease with pathogenic mtDNA mutations. MtDNA is transmitted maternally only and it has been proposed that nuclear transfer techniques may be an approach to prevent the transmission of human mtDNA disease

Pronuclear transfer program is a reproductive method of transferring the nuclear DNA of a fertilized egg into a donor egg from which nuclea  DNA has been removed. This technique is used to prevent maternally inherited mitochondrial DNA abnormalities.

Hence, option d is correct.

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