Which organ is primarily affected by cirrhosis?

Cirrhosis is primarily a liver condition characterized by the progressive replacement of healthy liver tissue with scar tissue, leading to a decline in liver function. This scarring impairs the liver's ability to process nutrients, produce essential proteins, and clear toxins from the bloodstream. The liver plays a crucial role in various metabolic processes, including the synthesis of clotting factors, bile production for digestion, and the metabolism of drugs and hormones.

As cirrhosis advances, various complications can arise, such as portal hypertension, liver failure, and increased risk of liver cancer. Therefore, it is the liver that is primarily affected by cirrhosis, making it the correct answer in this context. Other organs, such as the heart, lungs, and kidneys, may experience secondary effects due to systemic complications of liver dysfunction, but they are not directly impacted by the disease process of cirrhosis itself.