## Core Concept
The growth of the mandible, or lower jawbone, is a complex process involving various sites and mechanisms. One key aspect of mandibular growth is its ability to increase in length, which is crucial for the proper alignment of teeth and the overall facial structure. This growth can occur through different processes, including apposition of new bone.

## Why the Correct Answer is Right
The correct answer, **C. ramus**, is right because the mandible grows longer by the apposition of new bone on the posterior surface of the ramus. The ramus of the mandible is the vertical part that connects the body of the mandible to the condyle. Growth at the ramus allows for an increase in the length of the mandible. This process involves bone remodeling where bone is resorbed on the anterior surface and formed on the posterior surface of the ramus, effectively moving the mandible forward and downward.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because the condyle itself is a site of growth, but the primary mechanism of increasing mandibular length through apposition of new bone is not described as occurring on its surface in the context provided.
- **Option B:** This option is incorrect because, while the body of the mandible does experience growth, the specific process of increasing mandibular length through apposition of new bone on its posterior surface is more accurately attributed to the ramus.
- **Option D:** This option is incorrect because the alveolar process, which supports the teeth, does experience growth and bone remodeling, but it is not the site for the apposition of new bone to increase mandibular length in the manner described.

## Clinical Pearl / High-Yield Fact
A key point to remember is that mandibular growth occurs at specific sites, including the condyle (where endochondral ossification plays a role) and the ramus (where intramembranous ossification contributes to growth). Understanding these growth patterns is crucial for orthodontic and orthognathic surgical planning.

## Correct Answer: C. ramus