Please answer this question..

Dear Student, A) The hollow spaces in the hip bone are called cavity. B) The thigh bones fit into the cavity to form a ball and socket joint. C)The knee joint is a hinge type synovial joint, which mainly allows for flexion and extension (and a small degree of medial and lateral rotation) whereas The hip joint is a ball and socket synovial joint, formed by an articulation between the pelvic acetabulum and the head of the femur. It forms a connection from the lower limb to the pelvic girdle, and thus is designed for stability and weight. Regards