Answer:
the correct answer is A) rate of urbanization and pollution
Answer:
D) Each solar system contains billions of galaxies
Think, there are no other galaxies from the sun to Pluto (not a planet but still in our solar system) and the answer said EACH solar system and, a Galaxy contains solar systems not the other way around.
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.
Vietnamese immigrants are much more likely to be naturalized U.S. citizens than the overall immigrant population. In 2014, 76 percent of the 1.3 million Vietnamese immigrants residing in the United States were naturalized citizens, compared to 47 percent of the overall foreign-born population
