**Core Concept**
The nutrient arteries in long bones are responsible for supplying oxygen and nutrients to the medullary cavity. In the lower limbs, these arteries arise from various branches of the femoral and popliteal arteries. For the fibula, a long, slender bone in the lower leg, the nutrient artery arises from a specific branch that supplies the bone's medullary cavity.

**Why the Correct Answer is Right**
The peroneal artery, a branch of the posterior tibial artery, gives off the nutrient artery to the fibula. This artery enters the bone through a small foramen, typically located on the posterior aspect of the fibula, and supplies the medullary cavity with oxygen and nutrients. The peroneal artery is responsible for supplying the lateral aspect of the lower leg, including the fibula, and its branches play a crucial role in maintaining bone health.

**Why Each Wrong Option is Incorrect**
**Option B:** The anterior tibial artery primarily supplies the anterior aspect of the lower leg, including the tibia, and is not responsible for supplying the fibula.
**Option C:** The posterior tibial artery gives off the peroneal artery, but it is not the direct source of the nutrient artery to the fibula.
**Option D:** The popliteal artery is the main artery of the knee, giving off branches to the knee joint and surrounding muscles, but it is not directly responsible for supplying the nutrient artery to the fibula.

**Clinical Pearl / High-Yield Fact**
When examining the lower leg, it is essential to identify the nutrient foramen on the posterior aspect of the fibula, as this is the entry point for the nutrient artery. This knowledge is crucial for surgeons and radiologists when performing procedures involving the fibula.

**✓ Correct Answer: A. Peroneal artery**