**Core Concept**
The talus bone in the foot has several ligaments that provide stability to the ankle joint. The ligament below the head of the talus is a specific structure that plays a crucial role in ankle stability.

**Why the Correct Answer is Right**
The correct answer is the posterior talofibular ligament (PTFL), which is a strong ligament that connects the posterior surface of the head of the talus to the fibula. The PTFL is one of the primary stabilizers of the ankle joint, providing medial support and preventing excessive inversion of the foot. This ligament is often injured in ankle sprains, particularly in cases of inversion injuries.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct ligament. There are other ligaments in the ankle joint that are not directly related to the head of the talus.
**Option B:** This option is incorrect because it is not a specific ligament below the head of the talus. The anterior talofibular ligament (ATFL) is another ligament that connects the talus to the fibula, but it is located on the anterior surface of the head of the talus.
**Option C:** This option is incorrect because it is not a specific ligament below the head of the talus. The calcaneofibular ligament connects the calcaneus to the fibula, but it is not directly related to the head of the talus.

**Clinical Pearl / High-Yield Fact**
The posterior talofibular ligament (PTFL) is a common site of injury in ankle sprains, particularly in cases of inversion injuries. It is essential to diagnose and treat PTFL injuries promptly to prevent chronic ankle instability and long-term complications.

**Correct Answer:** C. Posterior talofibular ligament