The main idea of the passage is Living-donor liver transplantation offers a lifesaving alternative to whole-liver transplantation. How does the detail in bold develop the main idea?
We cannot survive without our livers, which remove waste products from our blood and produce bile to break down fats, among several other important functions. People with liver failure can be treated with whole-liver transplant surgery, in which a liver is taken from the body of a recently deceased person and placed into the body of a recipient. However, because the number of livers available for this type of transplant is extremely limited, whole-liver transplantation cannot be provided to all of the thousands of people on the waiting list for a liver. Living-donor liver transplants offer a solution. In a living-donor transplant, a person with a healthy liver donates part of his or her liver to replace the failing liver of another person. Because of the liver's amazing ability to regenerate itself, both the donor and the recipient will grow normal-sized livers in a matter of months. Thanks to living-donor transplantation, numerous lives have been saved.

1. It explains why whole-liver transplantation is preferred.
2 It identifies a serious limitation of whole-liver transplants