Final answer:
The major difference is that the pelvic girdle is more firmly attached to the vertebral column than the pectoral girdle, making it better suited for weight-bearing. The pelvic girdle's robust construction and limited mobility provide a stable foundation, compared to the pectoral girdle's focus on upper limb mobility.
Step-by-step explanation:
You asked about the major differences between the pelvic girdle and the pectoral girdle that allow the pelvic girdle to bear the weight of the body. The correct answer is d) The pelvic girdle is more firmly attached to the vertebral column than the pectoral girdle. This is because the pelvic girdle is part of the appendicular skeleton that attaches to the lower limbs and bears the body's weight during locomotion. It is securely attached to the axial skeleton by strong ligaments and has deep sockets with robust ligaments that securely attach the femur.
The pelvic girdle is strengthened by two large hip bones, which join together at the pubic symphysis in the front and with the sacrum bone at the back. This design ensures that the pelvic girdle can support and stabilize the body, making it less mobile but more suitable for weight-bearing compared to the pectoral girdle. The pectoral girdle, in contrast, consists of the clavicles and the scapulae that support the shoulder and are highly mobile to enable a wide range of movements for the upper limbs.
The pelvic girdle's limited range of motion and robust nature stabilize and support the body, while the pectoral girdle's mobility enhances the movements of the upper limbs.