Final answer:
The proposition that certain primate traits occurred in response to the availability of fruit and flowers following the spread of angiosperms is known as the angiosperm theory.
Step-by-step explanation:
The proposition that certain primate traits, such as visual acuity, occurred in response to the availability of fruit and flowers following the spread of angiosperms is known as the angiosperm theory.
This theory suggests that the basic primate traits developed in coevolution with the rise of flowering plants. Flowering plants provided resources like nectar, seeds, and fruits, which led to the development of ancestral forms of major groups of modern birds and mammals. Primates needed fine visual and tactile discrimination to feed on small food items found among the branches and stems of flowering plants.