Final answer:
Modern humans are believed to have left Africa approximately 60,000 years ago, following earlier migrations that began around 100,000 years ago, as supported by the 'out of Africa' model. Option C is correct.
Step-by-step explanation:
Fossil evidence suggests that modern humans left Africa around 60,000 years ago. This timing aligns with archaeological findings that show a dispersion of humans throughout Africa, Asia, Europe, and Australia by 40,000 years ago.
Early humans, after their emergence in Africa around 200,000 years ago, began a gradual migration out of the continent. The 'out of Africa' model supports the idea that modern humans began to expand out of Africa about 100,000 years ago, eventually leading to their presence across the globe.