The hip bone is formed by three parts: ilium, ischium, and pubis. At birth, these three components are separated by hyaline cartilage. They join each other in a Y-shaped portion of cartilage in the acetabulum. By the end of puberty the three regions will have fused together, and by the age of 25 they will have ossified. The two hip bones join each other at the pubic symphysis. Together with the sacrum and coccyx, the hip bones form the pelvis.

Answer this question based on the passage: where do the ilium the ischium and the pubis meet? OK. Let's think. My stream of consciousness:
The important part for answering this question is: They join each other in a Y-shaped portion of cartilage in the acetabulum. The answer is in the acetabulum.