**Core Concept**
The question is testing the understanding of the anatomy and function of the muscles of mastication. The muscles of mastication are a group of muscles responsible for the movement of the mandible, which includes the temporalis, masseter, medial pterygoid, lateral pterygoid, and digastric muscles.

**Why the Correct Answer is Right**
The correct answer is the lateral pterygoid muscle, which has an opposite and independent function compared to the other muscles of mastication. The lateral pterygoid muscle has two heads: the superior head and the inferior head. The superior head of the lateral pterygoid muscle elevates the mandible, whereas the inferior head depresses the mandible. This unique function allows the lateral pterygoid muscle to move the mandible in an opposite direction to the other muscles of mastication.

**Why Each Wrong Option is Incorrect**
* **Option A:** The temporalis muscle primarily elevates the mandible, which is not an opposite function to the other muscles of mastication.
* **Option B:** The masseter muscle also elevates the mandible, similar to the temporalis muscle, and does not have an opposite function.
* **Option D:** The medial pterygoid muscle elevates the mandible, and while it has some additional functions, it does not have an opposite and independent function like the lateral pterygoid muscle.

**Clinical Pearl / High-Yield Fact**
The lateral pterygoid muscle is the only muscle of mastication that has a dual action, with the superior head elevating the mandible and the inferior head depressing the mandible. This unique function allows for the precise movement of the mandible during mastication.

**Correct Answer:** C. Lateral pterygoid muscle.