Final answer:
The key benefit of bipedalism that is NOT a factor is reduced risk of predation option (d).
Step-by-step explanation:
The question is assessing knowledge of the advantages of bipedalism. Of the options given, the one that is NOT one of the key benefits of full-time bipedalism is d) Reduced risk of predation. Although bipedalism offers numerous advantages, such as energy efficiency, an enhanced vision of the surrounding environment, and improved thermoregulation by exposing more of the body's surface to air, it does not necessarily confer a reduced risk of predation. In fact, standing upright can make an organism more visible to predators. Bipedalism evolved for various reasons, but reduction of predation risk is not typically highlighted as a main factor.