President Kennedy tried to keep communism out of Vietnam by "(C) providing the southern Vietnamese government with American <span>military advisers," since Kennedy felt that this was a way to "contain" communism without committing many US troops on the ground. </span>
The correct answer is: 3 trillion dollars
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.
