Final answer:
The features described suggest that the pelvis belongs to a female individual.
Step-by-step explanation:
The features described in the question - wide sciatic notches, a wide, "U-shaped" subpubic angle, and long, rectangular-shaped pubic bones - are characteristic of the female pelvis. These features are adaptations for childbirth, as the female pelvis is wider and more spacious than the male pelvis. The male pelvis, on the other hand, is narrower and deeper.