The correct option is
D ilium
The pelvic girdle is located in the lower part of the trunk. It consists of three bones that are upper ileum, lower ischium and inner pubis, they fuse to form a stout hip bone. Ventral wall of the pubis has a small bone which is known as cotyloid. The acetabulum is formed by ilium, ischium and pubis, but in mammals, pubis is replaced by cotyloid bone.
So, the correct option is 'ilium'