The answer is B, they conquered
The correct answer is B) No historians have written about the era that preceded the ancient era.
The option that could be a reason why humans know very little about the time before the ancient era is that no historians have written about the era that preceded the ancient era.
We are referring to what is cold prehistory, the time where events occurred before the existence of written records. Historians write what they can research or interpret written records from the past such as the clay tablets of Sumer-Mesopotamia or the Egyptians glyphs due to the Rosetta Stone. But without written records, all is speculation, that is why humans know so little about prehistory.
North and South Korea have grown apart as a result of their vastly differing ideologies. North Korea is a communist country with very strict restrictions on the movement of its citizens. The North Korean regime is well-known for its cruelty. South Korea, on the other hand, is a democratic country with an open-market economy. In a nutshell, both North and South Korea have radically different political and economic systems. They have been two nations for over sixty years.