**Core Concept**
The maxillary sinus communicates with the nasal cavity through the semilunar hiatus (also known as the semilunar canal) in the middle meatus. This is a critical anatomical landmark for the drainage of the maxillary sinus.

**Why the Correct Answer is Right**
The maxillary sinus opens into the middle meatus at the level of the semilunar hiatus, which is a small slit-like opening. This opening is located between the uncinate process of the ethmoid bone and the bulla ethmoidalis. The drainage of the maxillary sinus is facilitated by the semilunar hiatus, which allows mucus and debris to flow out of the sinus and into the nasal cavity.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the maxillary sinus does not open into the superior meatus, which is a different location in the nasal cavity.
* **Option B:** This option is incorrect because the maxillary sinus does not open into the inferior meatus, which is also a different location in the nasal cavity.
* **Option D:** This option is incorrect because the maxillary sinus does not open into the nasopharynx, which is a different area of the respiratory tract.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the maxillary sinus opens into the middle meatus at the level of the semilunar hiatus, which is a critical anatomical landmark for the drainage of the maxillary sinus. This knowledge is useful for understanding the pathophysiology of sinusitis and for performing endoscopic sinus surgery.

**Correct Answer:** C.