Which bones in the human body are found in the gluteal region?

"It is clearly found in the gluteal region of the human body" clearly written in the description. Obviously easy then! Personally I didn't find it that easy!

If you suffer from lower back pain you definitely know this one!

the sacrum and ilium are both found in the gluteal region

Player #21493392, the answer said "bones" so the 2 answers should be acceptable. But since this game only allows 1 right answer, the ilium is"clearly in the gluteal region" while the sacrum,at the end of spine, clearly divides the buttocks.

gluteal muscles attach to both the sacrum and ilium

What about the ilium?