What organ is primarily at risk due to venous insufficiency?

Venous insufficiency occurs when the veins have difficulty sending blood from the limbs back to the heart, often leading to an accumulation of blood in the lower extremities. This condition results in increased venous pressure, which can ultimately cause a variety of complications. The skin is particularly affected due to the disruption of normal blood flow and the resultant issues, including increased pressure and edema.

In cases of chronic venous insufficiency, the skin may undergo significant changes. These changes can manifest as discoloration, ulcers, or dermatitis, indicating that the skin is directly impacted by the inadequate venous return. Over time, if left untreated, venous insufficiency can result in venous ulcers, which are challenging to heal and may lead to more serious complications.

While the heart, lungs, and liver might have associations with venous health generally, they are not as directly impacted by venous insufficiency as the skin is. The primary risks associated with venous insufficiency predominantly manifest in the skin due to the localized effects of the condition, making it the correct answer.