**Core Concept**
The frontal sinus is one of the paranasal sinuses, and understanding its drainage pathway is crucial for diagnosing and managing frontal sinusitis. The frontal sinus is a paired structure located in the frontal bone, and its drainage is facilitated by a specific anatomical structure.

**Why the Correct Answer is Right**
The frontal sinus drains into the anterior part of the nose through the frontal recess, which is a narrow channel located in the anterior wall of the frontal sinus. This channel is continuous with the infundibulum, a funnel-shaped structure that connects the frontal sinus to the anterior ethmoidal cells. The drainage from the frontal sinus is facilitated by the action of mucociliary clearance and the presence of cilia in the nasal mucosa. The frontal sinus drainage pathway is critical for maintaining the normal physiology of the paranasal sinuses.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the frontal sinus does not drain into the posterior ethmoidal cells.
**Option B:** This option is incorrect because the frontal sinus does not drain into the sphenoid sinus.
**Option C:** This option is incorrect because the frontal sinus does not drain into the maxillary sinus.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the frontal sinus drainage pathway is a critical factor in the development of frontal sinusitis, particularly in cases of chronic or recurrent sinusitis. Understanding the normal anatomy and physiology of the frontal sinus is crucial for diagnosing and managing this condition.

**Correct Answer:**
**D**. The frontal sinus drains into the anterior part of the nose through the frontal recess.