Madison wants to give a kidney to her older sister. what type of organ transplant will this be?

Kidney transplant

Explanation:

There are different types of organ transplant with each name derived from which organ is being transplanted.

In this scenario of Madison and her older sister, the kidney organ is involved, so it is called a kidney transplant

A kidney transplant, in medicine, is a surgical procedure carried out to replace an abnormal functioning kidney with an healthy or functioning one. The kidney can be gotten from a living source or dead source.

In this case, Madison is donating to her sister, so it can be called a living-donor kidney transplant.