**Core Concept**
The nasal septum is a critical anatomical structure separating the two sides of the nasal cavity. It is formed by the cartilaginous and bony components, which provide support and maintain the nasal passages' patency. The septum's formation involves the fusion of the medial nasal prominences during embryonic development.

**Why the Correct Answer is Right**
The nasal septum's cartilaginous portion is primarily formed by the septal cartilage, which is a single piece of cartilage that develops from the fusion of the medial nasal prominences. This process occurs during the 6th to 8th weeks of gestation. The septal cartilage provides the framework for the nasal septum, while the bony portion is formed by the perpendicular plate of the ethmoid bone, the vomer bone, and the nasal crest of the maxillary bone.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as the nasal septum's formation involves the fusion of the medial nasal prominences, not the lateral nasal prominences.
* **Option B:** This option is incorrect as the vomer bone is a major contributor to the bony portion of the nasal septum, not the cartilaginous portion.
* **Option C:** This option is incorrect as the perpendicular plate of the ethmoid bone is a major contributor to the bony portion of the nasal septum, not the cartilaginous portion.

**Clinical Pearl / High-Yield Fact**
The nasal septum's deviation can lead to nasal obstruction, reduced olfaction, and chronic nasal congestion. Understanding the embryonic development of the nasal septum is crucial for diagnosing and treating septal deviations.

**Correct Answer: B. Vomer bone**