Final answer:
Structure "G" is the joint capsule, a fibrous connective tissue structure that encloses the joint cavity and is attached to each bone near the articulating surface in a synovial joint.
Step-by-step explanation:
If structure "G" in the diagram of a synovial joint refers to the fibrous connective tissue structure that encloses the joint cavity, then the correct answer would be joint capsule (A). The joint capsule is an important structural feature of synovial joints, which are the most common type of joints in the body. It forms the walls of the joint cavity and is attached to each bone just outside the area of the bone's articulating surface. This capsule allows for the movement between the adjacent bones, which is facilitated by the presence of synovial fluid within the capsule. Articular cartilage, on the other hand, refers to the thin layer of hyaline cartilage that covers the articulating surfaces of bones within the synovial joint. Therefore, when you're asked which synovial joint structure is labeled "G", and if "G" is referring to the encapsulating structure, then A) joint capsule is the correct answer.