Answer:
Nature contributes substantially to the monkeys' preference for visual novelty.
Explanation:
Given that, despite the fact, the researcher raised these unrelated macque monkeys in a similar or identical laboratory environment, yet, he finds large differences among these monkeys in their preference for novel visual stimuli.
This shows that, Nature, which is a characteristics of their unrelated attributes, contributes substantially to their preference in visual novelty, than Nurture, which is the influence they must have gotten through their living in identical laboratory environment.
Hence, the researcher might legitimately conclude concerning the relative contributions of nature or nurture, that, Nature contributes substantially to the monkeys' preference for visual novelty.