Which of the following is most closely identical to the formation of twins? a) cell cloning b) therapeutic cloning c) use of adult stem cells d) embryo transfer e) organismal cloning

The correct answer is option E, that is, organismal cloning.  

The procedure of generating genetically similar individuals of an organism either artificially or naturally is known as cloning. The reproductive cloning or organismal cloning is the process of producing a novel multicellular organism, genetically similar to another. Primarily, this kind of cloning is an asexual reproduction process, where inter-gamete contact or fertilization do not occur. Thus, the process is most closely similar to the formation of twins.  

cell regulation is conducted by special proteins.