Complex sentence: Legalization of human organ trading has been opposed by a variety of human rights groups like the Organs Watch, a group established by medical anthropologist Nancy Scheper-Hughes who was instrumental in exposing illegal international organ selling rings.
Split into simpler sentences: Legalization of human organ trading has been opposed by a variety of human rights groups. One such group is Organs Watch, which was established by Nancy Scheper-Hughes-a medical anthropologist who was instrumental in exposing illegal international organ-selling rings.