The right option is; Extreme cases can lead to gangrene, which can require removal of a limb.
“Extreme cases can lead to gangrene, which can require removal of a limb” is the statement that best replaces the sentence. Buerger's disease is a rare illness of the arteries and veins in the arms and legs that usually affect smokers. This disease can damage the skin tissues and may result in gangrene (death of body tissues) which can make all or part of a limb to be amputated (removed).