**Core Concept**
The anterior compartment of the leg contains muscles responsible for dorsiflexion and eversion of the foot. These muscles are primarily innervated by the deep peroneal nerve, a branch of the common peroneal nerve.

**Why the Correct Answer is Right**
The anterior compartment muscles include the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius. These muscles work together to facilitate dorsiflexion of the foot, which is essential for activities such as walking and balance. The deep peroneal nerve, which innervates these muscles, arises from the common peroneal nerve in the lateral compartment of the leg.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the muscles of the anterior compartment do not include the peroneus longus, which is actually located in the lateral compartment of the leg and is responsible for eversion of the foot.
* **Option B:** This option is incorrect because the muscles of the anterior compartment do not include the flexor hallucis longus, which is actually located in the posterior compartment of the leg and is responsible for flexion of the great toe.
* **Option C:** This option is incorrect because the muscles of the anterior compartment do not include the gastrocnemius, which is actually located in the posterior compartment of the leg and is responsible for plantarflexion of the foot.

**Clinical Pearl / High-Yield Fact**
The anterior compartment syndrome is a condition characterized by increased pressure within the anterior compartment, leading to muscle weakness and pain. This condition often occurs in athletes who participate in sports that involve running or repetitive ankle movements.

**Correct Answer: A. Peroneus longus.**