Is a tissue membrane positioned in thin cavities between bones in movable joints.

The correct answer is "synovial membrane." The synovial membrane is a tissue that primarily produces synovial fluid between the joints which serves as a lubricant. Apart from making synovial fluid, it lines joint cavities, tendon sheaths, and the bursa which is a sac filled with fluid that is located between the tendons and the bones.

A- a reduction in biodiversity