**Core Concept**
The process of ossification refers to the transformation of cartilage into bone, a crucial step in the development and growth of the skeletal system. In the human body, this process can occur through either intramembranous ossification, where bone tissue is directly formed from mesenchymal cells, or endochondral ossification, where cartilage is gradually replaced by bone tissue.

**Why the Correct Answer is Right**
The commonest cartilage to ossify is the **hyaline cartilage**. This type of cartilage is found in the growth plates of long bones and is responsible for the longitudinal growth of the skeleton. During endochondral ossification, hyaline cartilage is gradually replaced by bone tissue, allowing for the growth and development of the long bones. The process begins with the invasion of blood vessels and the deposition of bone matrix, eventually leading to the formation of bone tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** **Fibrocartilage** is a type of cartilage found in areas of high stress and tension, such as the intervertebral discs and the pubic symphysis. While it does undergo changes with age, it is not the commonest cartilage to ossify.
**Option B:** **Elastic cartilage** is found in areas where flexibility is required, such as the external ear and the epiglottis. It does not undergo significant ossification and remains flexible throughout life.
**Option C:** **Cartilage** is a broad term that encompasses several types of cartilage, including hyaline, fibrocartilage, and elastic cartilage. While some types of cartilage ossify, the question specifically asks for the commonest cartilage to ossify.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the process of ossification is a critical step in the development and growth of the skeletal system. Understanding the types of cartilage and the process of ossification can help clinicians diagnose and manage conditions related to abnormal bone growth and development.

**Correct Answer: C.**