**Core Concept:** The frontal sinus is a group of air-filled cavities in the skull, located in the ethmoid bone. They are visible on imaging studies like CT scan and MRI scans. The correct orientation for frontal sinus visualization is essential for accurate diagnosis and treatment planning.

**Why the Correct Answer is Right:** The correct answer, **D**, indicates the frontal sinus should be evaluated in a coronal orientation on imaging studies. In a coronal view, the frontal sinus opens directly into the frontal recess, which is a blind-ending passage that connects the frontal sinus to the nasal cavity. This orientation allows for better visualization of the sinus complex and its relationship to surrounding structures, such as the frontal sinuses, frontal recess, and the ethmoid sinus complex.

**Why Each Wrong Option is Incorrect:**

A. **Option A (axial view):** An axial view only shows a cross-section of the frontal sinus and does not provide the complete picture of its relationship with surrounding structures.

B. **Option B (coronal view):** While a coronal view can provide insight into the frontal sinus cavity, it does not highlight the connection between the frontal sinus and the frontal recess, which is crucial for diagnosis and treatment planning.

C. **Option C (sagittal view):** A sagittal view provides a good overview of the skull base, but it does not specifically focus on the frontal sinus and its relationship with the frontal recess.

**Clinical Pearl:** In clinical practice, radiologists often use a combination of axial, coronal, and sagittal views to comprehensively evaluate the frontal sinus and surrounding structures. However, for this MCQ, focusing on the relationship between the frontal sinus and frontal recess justifies choosing option D (coronal view) as the best view for frontal sinus visualization.

**Correct Answer:** **D.** Coronal view