Is the question multiple choice?
Answer:
Technologies such as plows and irrigation often played a direct part in transforming the landscape of the United States in the 1800s.
Answer:
1.Atria push blood into the ventricles
2.Venticles push blood out of the heart.
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Below are the choices. the answer is C.
A) mass extinctions, leading to bottleneck effect
B) major evolutionary innovations, leading to rafting to nearby continents
C) a variety of empty ecological niches, leading to adaptive radiation
<span>D) adaptive radiation, leading to founder effect</span>