Final answer:
The key focus of naturalistic assumptions about existence and man is scientific progress, which is based on empirical evidence and rational thought, excluding supernatural explanations.
Step-by-step explanation:
The key focus of naturalistic assumptions about existence and man is c) Scientific progress. Naturalism is grounded in the belief that everything arises from natural properties and causes, and supernatural or spiritual explanations are excluded or discounted. This philosophical viewpoint is closely associated with the scientific method, which relies on empirical evidence and rational thought. The modern period, particularly during the Enlightenment, was marked by significant developments in many disciplines founded on this naturalistic approach. The rejection of a priori reasoning in favor of empirical study led to advances in understanding the physical world and improving the human condition.
Throughout history, from ancient Greece to the Enlightenment, the natural world was studied with the intent of using this knowledge to benefit human societies, which aligns with the naturalistic viewpoint of focusing on analyzing and utilizing the material world for human purposes. The emphasis is on empirical evidence and the application of reason, both of which are essential components of scientific progress.