**Core Concept**
The joint between the epiphysis and diaphysis of a long bone is a type of synovial joint that allows for limited movement and enables growth in length of the bone. This joint is characterized by a cartilaginous plate called the growth plate or physis, which separates the epiphysis from the diaphysis.

**Why the Correct Answer is Right**
The joint between the epiphysis and diaphysis is a type of synovial joint called an epiphyseal plate or growth plate. The growth plate is a cartilaginous plate that separates the epiphysis from the diaphysis and allows for longitudinal growth of the bone. The growth plate is composed of a zone of resting cells, a zone of proliferating cells, and a zone of hypertrophic cells. The growth plate is richly innervated and has a rich blood supply, which allows for the continuous growth and remodeling of the bone.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the joint between the epiphysis and diaphysis is not a type of fibrous joint, which is characterized by a dense connective tissue that provides little to no movement.

**Option B:** This option is incorrect because the joint between the epiphysis and diaphysis is not a type of cartilaginous joint, which is characterized by a hyaline cartilage that provides some movement.

**Option C:** This option is incorrect because the joint between the epiphysis and diaphysis is not a type of pivot joint, which is a type of synovial joint that allows for rotational movement.

**Clinical Pearl / High-Yield Fact**
The growth plate is a critical structure that allows for the continuous growth and remodeling of long bones. Injuries to the growth plate, such as fractures or osteochondritis dissecans, can lead to growth disturbances and abnormalities in bone length and shape.

**Correct Answer: D. Synovial joint**