What are the three main categories of joints in the human body?

The three main categories of joints in the human body are correctly identified as synovial, cartilaginous, and fibrous.

Synovial joints are characterized by a fluid-filled joint cavity that allows for a wide range of motion. These joints include examples such as knees, elbows, and shoulders, which are crucial for movement and flexibility in various activities.

Cartilaginous joints, in contrast, are connected entirely by cartilage, providing some degree of movement while maintaining stability. An example of this type of joint is the intervertebral discs in the spine, which allow for limited motion while absorbing shock.

Fibrous joints are fixed joints where the bones are held together by dense connective tissue. These joints do not allow for movement and serve to provide strength and protection, with sutures in the skull being a prime example.

This classification of joints is essential for understanding their structure, function, and role in the human body, as each type serves distinct anatomical purposes. The other options do not accurately reflect the recognized categories of joints, leading to less clarity in their biological functions.