Final answer:
Primates are characterized by their stereoscopic vision for depth perception and large brains for higher cognitive functions. These evolved traits are part of their adaptations for navigating arboreal environments.
Step-by-step explanation:
The two key characteristics of a primate that distinguish them from other mammals are c) stereoscopic vision and d) a larger brain. Primates, including humans, have evolved adaptations primarily for climbing trees, as indicated by their arboreal heritage. Such adaptations include a rotating shoulder joint and thumbs that are widely separated from fingers, which aid in grasping. The stereoscopic vision allows primates to perceive depth and gauge distances accurately, a critical ability for navigating complex arboreal environments. Additionally, primates have proportionally large brains compared to many other mammals, which correlates with greater cognitive abilities and behavioral complexity. These traits provide primates with manual dexterity and evolved vision, allowing for skilled manipulation of objects and precise visual perception in varied environments.