In 1974 an almost complete skeleton of Australopithecus afarensis was found in Africa. The fossil was called "Lucy." Lucy had apelike shoulders and forelimbs. However, the pelvis indicates that she was bipedal. The size of her brain was small, an apelike characteristic. What did the study of Lucy help paleoanthropologists determine? Select TWO correct answers.

A. Hominids had large brains before they walked upright.

B. Hominids walked upright before they had large brains.

C. Hominids are primates with opposable thumbs.

D. Human characteristics evolved at different rates and, therefore, at different times.