The correct answer is illium, which is one of the three bones that make up the pelvis. The pelvis is a large, sturdy bone structure located at the base of the spine, and it consists of three fused bones: the illium, ischium, and pubis. The illium is the largest and most superior of the three bones, forming the upper part of the pelvis. It has a broad, curved shape and plays a crucial role in supporting the weight of the upper body and connecting the spine to the lower limbs.