**Core Concept**
Cephalometric analysis is a radiographic technique used to assess the relationship between the upper and lower jaws, as well as the position of various craniofacial structures. Accurate identification of cephalometric points is crucial for diagnosing and planning orthodontic and orthognathic treatments.

**Why the Correct Answer is Right**
The point representing the centre of the ramus of the mandible is the **Point A**. This point is located at the intersection of the mandibular ramus and the mandibular plane. It is an important reference point used in cephalometric analysis to assess the vertical dimension of the face and the position of the mandible.

**Why Each Wrong Option is Incorrect**
**Option B:** Point B is actually the deepest point on the posterior face of the mandibular ramus, not the centre. It is used as a reference point for assessing the sagittal relationship between the maxilla and the mandible.

**Option C:** Point C is the condylion, which is a landmark used to measure the vertical dimension of the face. It is located at the lowest point of the mandibular condyle, but it does not represent the centre of the ramus.

**Option D:** Point D is the gonion, which is a landmark used to measure the mandibular angle. It is located at the intersection of the ramus and the angle of the mandible, but it does not represent the centre of the ramus.

**Clinical Pearl / High-Yield Fact**
When performing cephalometric analysis, it is essential to accurately identify and mark the correct points on the radiograph to ensure accurate diagnosis and treatment planning. Points A, B, C, and D are just a few of the many landmarks used in cephalometric analysis.

**Correct Answer:** A. Point A.