How is the female sacrum and tailbone differentiated from the male?

The differentiation of the female sacrum and tailbone (coccyx) from the male is primarily associated with the pelvic structure and its adaptation for childbirth in females. The correct choice highlights that females typically have a shorter tailbone and a sacrum that is curved outward.

In females, the sacrum's outward curvature allows for a wider pelvic inlet, which is essential for accommodating the passage of a baby during childbirth. This adaptation results in a shorter and sometimes more flexible coccyx, which can also facilitate the process of delivery and provide a larger birth canal.

In contrast, male pelves are generally more robust and have a longer, straighter coccyx and a sacrum that may curve inward or be less pronounced, reflecting adaptations for bipedal locomotion rather than childbirth. The other choices present characteristics that do not accurately represent the anatomical differences between male and female pelves, focusing instead on attributes that don't align with the functional requirements of female anatomy in childbirth. Thus, the correct answer effectively summarizes these important distinctions.