**Core Concept**
Fibrous joints, also known as synarthrodial joints, are immovable or slightly movable joints that are united by dense connective tissue. They provide strong support and stability to the body, allowing for minimal movement.

**Why the Correct Answer is Right**
The first costochondral joint is an example of a cartilaginous joint, specifically a synchondrosis. It is a type of growth plate that connects the ribs to the sternum, allowing for growth and flexibility in the chest wall. This joint is characterized by hyaline cartilage connecting the ribs to the sternum, which is different from the fibrous joints that are held together by dense connective tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** Sutures of the skull are a type of fibrous joint that connects the bones of the skull together. They are immovable and provide a strong, stable structure for the brain.

**Option C:** The tooth socket is a fibrous joint that connects the tooth to the surrounding bone. It is a type of gomphosis, a fibrous joint that holds the tooth in place.

**Option D:** The inferior tibiofibular joint is a type of syndesmosis, a fibrous joint that connects the tibia and fibula bones in the lower leg. It is a fibrous joint that provides support and stability to the ankle.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that fibrous joints are classified into three subtypes: sutures, syndesmoses, and gomphoses. Understanding the characteristics of each subtype is crucial for accurate diagnosis and treatment of various orthopedic conditions.

**Correct Answer:**
✓ Correct Answer: B. First costochondral joint