Answer:
Darwin's main contribution to the theory of evolution was his theory of natural selection.
Explanation:
Natural selection is the phenomenon that some organisms from a particular population fit better into their environment, that is, are more likely to provide surviving offspring than less well-adapted organisms. The best adapted organisms will increasingly gain the upper hand within the population (survival of the fittest). It is thus one of the mechanisms of evolution. Mutations in, and recombinations of, the genetic material of the organisms cause the genetic variation in the population, allowing this selection.
The thing which was a major factor that threatened the major unity in the United States in the mid-19th century was:
<h3>The Great Depression</h3>
This refers to the period around 1929 in the United States which has a profound effect on the national economy.
This led to the failure of many banks, increase in unemployment and high deflation rates which all threatened the national unity.
Read more about Great Depression here:
brainly.com/question/441267
Answer:
Complex Carbohydrate
Explanation:
It is called complex because it cannot be broken down into digestible sugar molecules.\
Hope it is right
<span>Reconstruction encompassed three major initiatives: restoration of the Union, transformation of southern society, and enactment of progressive legislation favoring the rights of freed slaves. </span><span>The Constitution provided no guidance on secession or readmission of states.</span>
In the early 20th century, the primary <span>cause of the large-scale migration of African
Americans out of the rural South was "</span><span>(2) opportunities for jobs in northern factories" and better treatment by whites, in general. </span>
