Final answer:
The adaptive characteristic of bipedalism in the options listed is the longitudinal arch in the foot, essential for efficient walking and weight support.
Step-by-step explanation:
The adaptive characteristic of bipedalism among the options provided is the d) longitudinal arch in the foot. The development of this arch is key to the efficient bipedal locomotion seen in humans. It aids in supporting the body's weight and in providing leverage and shock absorption during walking. Other characteristics such as opposable thumbs, nails instead of claws, and convergent eyes are adaptations related to primate arboreal heritage or other functional needs, but they are not specifically adaptations for bipedalism.