Final answer:
The statement that no non-human primate is fully terrestrial and all spend time in trees is true. Primates have evolved to live in trees with specific adaptations such as hands and feet suitable for climbing, a rotating shoulder joint, and stereoscopic vision.
Step-by-step explanation:
Not all primates are adapted to a fully terrestrial environment, and indeed, all primates spend some time in trees. This statement is true. Primates evolved in trees and many of their traits are adaptations to an arboreal, or tree-dwelling, lifestyle. These traits include hands and feet that are suitable for climbing and brachiation, a rotating shoulder joint, widely separated big toes and thumbs for gripping branches, and stereoscopic vision for depth perception necessary to gauge distances while moving through the trees. Some primate species, such as baboons, are partially terrestrial but still possess these arboreal adaptations.