Modern humans, Homo sapiens...

[Volcano1985]

Modern humans, Homo sapiens,---- in Africa around 200,000 years ago and by about 30,000 years ago they ---- all other forms of early humans, such
as Neanderthals and Homo erectus.

A) have been evolving / replaced
B) would evolve / are replacing
C) were evolving / have replaced
D) evolved / had replaced
E) had evolved / had been replacing

Can you explain me why D? 200.000 years is not bigger than 30.000 years?

 

[Rover_KE]

What do you mean by 'not bigger than'?

200,000 years ago is further back in time than 30,000 years ago.

 

[Raymott]

What do you mean by 'not bigger than'?

200,000 years ago is further back in time than 30,000 years ago.

I think that's what is concerning Volcano. My guess is that he's assuming that the past perfect tense should apply to the event that happened first (ie. the longest time ago). The correct answer gives the opposite.

@ Volcano: You can't ignore all the others factors in the sentence. Let's break it in two - which is valid because this is essentially two sentences joined by a coordinating conjunction.
1. Modern humans, Homo sapiens, evolved in Africa around 200,000 years ago. 2. By about 30,000 years ago they had replaced all other forms of early humans, such as Neanderthals and Homo erectus.

1. uses the simple past because a specific time is mentioned.
2. uses the past perfect because, by the time 30,000 years ago came about, the event reported had occurred.
If you rejoin the sentences, nothing changes. It's trivially true that they had evolved before they replaced other humans, but this is not something the author thinks worth pointing out, and it's not the structure of the sentence.