**Core Concept**
The valvular component of the nasal passages refers to the turbinate bones and the nasal valves, which play a crucial role in regulating nasal airflow. The nasal valve area is the narrowest part of the nasal passage and is responsible for most of the resistance to airflow.

**Why the Correct Answer is Right**
When the lateral part of the cheek is retracted, it helps to open up the nasal valve area by increasing the diameter of the nasal passage. This allows for more airflow and improves nasal patency. The nasal valve area is a critical regulator of nasal airflow, and any obstruction in this area can lead to nasal congestion. By testing the valvular component of the nose, clinicians can assess the patency of the nasal valve area and identify any potential obstructions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because retracting the lateral part of the cheek does not directly affect the turbinate bones, which are the primary components of the nasal passages.

**Option B:** This option is incorrect because the alar fan or the alar crease is a fold of skin that runs from the nasal wing to the nostril, and it does not play a significant role in regulating nasal airflow.

**Option C:** This option is incorrect because the septum is a wall of cartilage and bone that separates the two sides of the nasal passages, and it is not directly affected by retracting the lateral part of the cheek.

**Clinical Pearl / High-Yield Fact**
The nasal valve area is the narrowest part of the nasal passage and is responsible for most of the resistance to airflow. Clinicians can improve nasal patency by using techniques such as nasal strips or dilators to open up the nasal valve area.

**Correct Answer: B. The alar fan or the alar crease is often used to assess the function of the nasal valve.