**Core Concept**
Lymphedema is a chronic condition characterized by the abnormal accumulation of protein-rich fluid in the interstitial tissue, leading to swelling and hardening of the affected limb. The most common cause of lymphedema is the obstruction of lymphatic vessels, which can result from various factors such as injury, infection, or surgical removal of lymph nodes.

**Why the Correct Answer is Right**
The correct answer is related to the removal of lymph nodes, which is a common cause of lymphedema. This is because lymph nodes play a crucial role in filtering lymph fluid and removing pathogens and waste products. When lymph nodes are removed or damaged, the lymphatic system's ability to drain fluid is impaired, leading to the accumulation of fluid in the affected limb. This is particularly relevant in cancer patients who undergo lymph node dissection as part of their treatment.

**Why Each Wrong Option is Incorrect**
* **Option A:** Injury to lymphatic vessels may cause lymphedema, but it is not the most common cause. Injury to lymphatic vessels is a more acute event and may not lead to chronic lymphedema.
* **Option B:** Infection can cause lymphedema, but it is not the most common cause. Infections such as cellulitis or lymphangitis can cause lymphedema, but they are typically acute and self-limiting.
* **Option C:** Filariasis is a parasitic infection that can cause lymphedema, but it is not the most common cause. Filariasis is a significant public health problem in certain parts of the world, but it is not the most common cause of lymphedema in developed countries.

**Clinical Pearl / High-Yield Fact**
Lymphedema can be prevented or managed with early recognition and treatment. Patients with a history of lymph node dissection or other risk factors for lymphedema should be monitored closely for signs of lymphedema, and treatment should be initiated promptly if symptoms develop.

**Correct Answer: D. Lymph node removal or damage.**