Answer:
1. Zygote
Explanation:
A zygote is formed due to the fertilization of the female egg by the sperm cell.
A zygote cell is eukaryotic in nature. It is also a diploid cell because it is the coming together of a sperm cell which is a haploid cell and a female egg which is also a haploid cell.
A zygote cell contains DNA from both the sperm and the egg.
This is why in other to change the DNA of a sexually reproducing organism after fertilization and have an new DNA present in every cell of the organism, the scientist would have to change the DNA in the Zygote.