The given diagram shows some of the parts of human skeleton.The function of the curves, labelled as I, II, III and IV, in the vertebral column is to

Explanation

The correct answer is Option D: The curves of the vertebral column increase its strength and flexibility. These curves help to distribute mechanical stress as the body moves, maintaining balance and enabling a range of motion. Option A is incorrect because the arms and legs are not directly affected by the vertebral column's curves. Option B is incorrect because the curves do not serve as primary attachment points for the pectoral and pelvic girdles. Option C, while partially true in terms of the vertebral column's function, does not address the specific purpose of the curves themselves, which is more about flexibility and distributing loads.