Final answer:
Biologists and anthropologists commonly attribute the development of bipedalism in hominids to natural selection, which favored adaptations that offered significant survival advantages, such as freeing hands for carrying tools and other objects.
Step-by-step explanation:
An explanation for the development of bipedalism in hominids that is often provided by anthropologists and biologists is D. Natural selection. The evolution of hominin bipedalism required significant anatomical changes, which suggests the benefits of these adaptations were large enough to be favored by natural selection. One key advantage may have been the ability to free the hands for carrying tools, food, or offspring, thereby increasing efficiency and adaptability. Over time, humans developed new skills and tools to meet the challenges they faced, adapting through cooperation and migration, and their anatomical and behavioral changes were shaped by the environments in which they lived.