A, cloning technology does not require male and female mating, and does not require the combination of sperm and eggs. It only needs to extract single cells from animals, cultivate them into embryos by artificial methods, and then transplant the embryos into the uterus of female animals to breed new individuals. Therefore, it belongs to asexual reproduction, so it does not meet the meaning of the question;
B, the nucleus is the genetic information base, and the genetic information of cloned animals mainly comes from the parents who provide the nucleus. Cloned animals have their own "mother", which is a ewe for nuclear donation, so it meets the meaning of the question;
C, the variation caused by transgenic technology is the variation caused by the change of genetic material, which is heritable, so it does not meet the meaning of the question;
D, organ transplantation will stimulate human lymphocytes and produce antibodies against organ survival. Therefore, there will be rejection. It belongs to human-specific immunity, which will recognize that it is a non-self component and thus produce rejection, and it belongs to the third line of defense. So it doesn't fit the meaning of the question.
Therefore, choose: B.