Early humans most likely experienced which of the following changes in climate and environment?

I think it is C change in climate revealing passageways for migration. Because early humans started in africa and went from there to everywhere

Evolution - have proposed a variety of ideas about how environmental conditions may have stimulated important developments in human origins. Diverse species have emerged over the course of human evolution, and a suite of adaptations have accumulated over time, including upright walking, the capacity to make tools, enlargement of the brain, prolonged maturation, the emergence of complex mental and social behavior, and dependence on technology to alter the surroundings.