Final answer:
The question matches articular cartilage on the head of the femur with the presence of GAG molecules, which is correct as GAGs are found in articular cartilage that covers bone surfaces within synovial joints. Synostosis, synovial membrane responsibilities, and the sequence of bone fracture repair presented in the other options are incorrectly matched.
Step-by-step explanation:
The correct match among the options provided for the question is: articular cartilage on the head of the femur : contains GAG molecules. This is because articular cartilage, which is a type of hyaline cartilage, contains glycosaminoglycans (GAGs) that help it to resist compression and reduce friction in synovial joints, such as the hip joint where the head of the femur articulates with the acetabulum of the pelvis.
A synostosis is not a type of joint but rather a site where two bones have fused completely over time, leaving no movement. The junction between the bones of the fingers is not a synarthrosis, as they are not immobile; they're diarthroses, freely movable synovial joints. The synovial membrane does not hold bones together; it produces synovial fluid within synovial joints. Lastly, in the repair of a bone fracture, the formation of a bony callus is not the second event; it generally follows the formation of a fibrocartilaginous callus.