**Core Concept**
Filariasis, caused by filarial parasites, leads to lymphatic obstruction due to the body's immune response and the parasite's life cycle. This results in chronic lymphedema and elephantiasis, a condition characterized by massive swelling of the affected limb.

**Why the Correct Answer is Right**
The correct answer is **Wuchereria bancrofti**, a species of filarial parasite that infects humans and causes lymphatic filariasis. The parasite's life cycle involves the microfilariae, which are transmitted to humans through the bite of an infected mosquito. Once inside the human body, the microfilariae develop into adult worms that live in the lymphatic vessels, causing obstruction and leading to chronic lymphedema. The body's immune response to the parasite further contributes to the lymphatic damage.

**Why Each Wrong Option is Incorrect**
* **Option A:** Brugia malayi is another species of filarial parasite that causes lymphatic filariasis, but it is not the primary cause of filariasis in humans.
* **Option B:** Loa loa, also known as the African eye worm, causes loiasis, a different type of filarial infection that affects the eye and skin, but not the lymphatic system.
* **Option C:** Onchocerca volvulus causes onchocerciasis, also known as river blindness, which affects the skin and eyes, but not the lymphatic system.

**Clinical Pearl / High-Yield Fact**
Remember that lymphatic filariasis is a major public health problem in tropical and subtropical regions, and it is one of the leading causes of chronic disability worldwide.

**Correct Answer: C. Brugia malayi**