Which of the following statements is TRUE according to the passage
A．Doctor Severino Antinori is strongly opposed to cloning human beings.
B．Up to now, seven kinds of animals have been cloned, including sheep, cats, humans and rabbits.
C．Professor Rudolf Jaenisch is carrying on an experiment on cloning an eight-week-old embryo.
D．Ronald Green doubts about the future successful birth of the so-called cloned embryo.