By 400,000 humans with a mix of homo erectus and homo sapien like features start to appear. their scientific name is

Homo neanderthalensis

Explanation:

Homo neanderthalensis, commonly known as Neanderthal, was a species of hominid that occurs in the fossil records around 430,000 years ago up until 40,000 years ago. This hominid lived in Europe, the Middle East, and the western half of Central Asia. The Neanderthal is a hominid that looks like a cross between the Homo sapiens and the Homo erectus. It is believed that this species of hominid was mostly carnivorous, and that the majority of the food came from hunting of animals, and much less from gathering plants. With the migration of the Homo sapiens into the territory of the Neanderthal though, its numbers started to quickly decline and it went extinct, but it left its DNA as the two species were interbreeding, so lot of people in Europe and Asia have a Neanderthal DNA, usually between 1 and 4%.

D. Would be the safest answer