Final answer:
The adolescent Homo erectus found in Nariokotome, Kenya, had postcranial traits similar to modern humans, with bipedalism being the correct answer from the given options.
Step-by-step explanation:
The adolescent discovered in Nariokotome, Kenya, attributed to Homo erectus, displayed various postcranial traits that are characteristic of modern humans.
Among the options provided, the correct answer to which postcranial trait the Homo erectus specimen had is B) Bipedalism. This species had human-like features such as bipedality, walking with a human gait, and humanlike feet with arches and ankles.
While they shared some traits with earlier hominins, such as a prominent brow and a downward-pointing nose, their bipedal locomotion was nearly as efficient as that of modern humans.