**Core Concept**
The posterior ethmoidal sinus is one of the paranasal sinuses, which are air-filled cavities within the skull that communicate with the nasal cavity through various drainage pathways. Understanding the anatomy of these pathways is crucial for diagnosing and managing sinus-related disorders.

**Why the Correct Answer is Right**
The posterior ethmoidal sinus drains into the superior meatus, which is a small, narrow passage in the lateral wall of the nasal cavity. This drainage pathway is essential for the clearance of mucus and debris from the posterior ethmoidal sinus. The superior meatus is located above the middle meatus, which receives drainage from the anterior ethmoidal sinuses, frontal sinus, and maxillary sinus.

**Why Each Wrong Option is Incorrect**
**Option A:** The spheno-ethmoidal recess is the drainage site for the sphenoid sinus, not the posterior ethmoidal sinus.
**Option C:** The middle meatus is the drainage site for the anterior ethmoidal sinuses, frontal sinus, and maxillary sinus, not the posterior ethmoidal sinus.
**Option D:** The inferior meatus is not a primary drainage site for any of the paranasal sinuses, and it is not associated with the posterior ethmoidal sinus.

**Clinical Pearl / High-Yield Fact**
Recall that the paranasal sinuses drain into various meatuses of the nasal cavity, and each sinus has a specific drainage pathway. This knowledge is essential for diagnosing and managing sinus-related disorders, such as sinusitis, which can be caused by blockage of these drainage pathways.

✓ Correct Answer: B. Superior meatus