Answer the following question given this paragraph: 

The ilium is the fan-like, superior region that forms the largest part of the hip bone. It is firmly united to the sacrum at the largely immobile sacroiliac joint (see Figure 8.12). The ischium forms the posteroinferior region of each hip bone. It supports the body when sitting. The pubis forms the anterior portion of the hip bone. The pubis curves medially, where it joins to the pubis of the opposite hip bone at a specialized joint called the pubic symphysis.


Q: What is the fan-like superior region that forms the largest part of the hip bone and is united to the sacrum at the largely immobile sacroiliac joint?


A:
ilium