GMAT Reading Comprehension (RC) | Re: A clone is a genetically identical copy of a living organism

3. According to the passage, which of the following is a potential obstacle to human cloning?
A. Lack of adequately prepared human eggs
B. Predetermination of DNA function within the adult body
C. Shortage of funding for additional research
D. Inability to pinpoint specific biological relationships within an egg
E. Unpredictability of chemical reactions within the uterus

where does the author say that predetermination of DNA function within the adult body