"Cloning" refers to asexual reproduction, that is, a pure cell line formed by the division and reproduction of the same ancestor cells, and the genes of each cell in this cell line are the same. For example, Dolly, a cloned sheep, uses mammary epithelial cells (somatic cells) as donor cells for nuclear transfer, and adopts the traditional embryo nuclear transfer method.
Grafting is one of the methods of artificial vegetative propagation of plants, that is, grafting branches or buds of one plant to stems or roots of another plant, so that the two connected parts grow into a complete plant. When grafting, the cambium of scion and rootstock should be closely combined to ensure the survival of scion.
Hybridization depends on whether the hybrids are the same species. As long as parents pollinate, according to Mendel's genetic theorem, offspring will have the corresponding characteristics of parents. Somatic cell fusion is a technique to double the chromosome number of plant cells or double the chromosome number. Organisms are prone to variation.
The breeding process of Dolly, a cloned sheep: ① Breast cells were taken from the mammary glands of a six-year-old female FenDorset white-faced sheep (A for short) and placed in low-concentration culture medium, and the cells gradually stopped dividing, which was called donor cell-cell culture. ② An unfertilized egg cell was taken from the ovary of a Scottish black-faced ewe (named B) and established. Leaving a seedless egg cell, called the recipient cell. ③ The donor cells and recipient cells were fused by electric pulse method, and finally the fused cells were formed. Electrical pulse can produce a series of reactions similar to natural fertilization process, so that the fused cells can divide and differentiate like fertilized eggs, thus forming embryonic cells. ④ Embryonic cells were transplanted into the uterus of another Scottish black-faced ewe (called C). Embryo cells further differentiated and developed, and finally Dolly sheep-embryo transfer was formed. Therefore, the biotechnology used by scientists to cultivate Dolly the sheep is cloning technology.
So choose B.