Onomatopoeia is literary device that copies natural sounds.
A simile is a comparison between two things using as or like.
Metaphor is a direct comparison between two things without the use of ‘as’ or ‘like’
Answer:

Douglass advocated equal justice and rights, as well as citizenship, for blacks. He begins his speech by modestly apologizing for being nervous in front of the crowd and recognizes that he has come a long way since his escape from slavery.
Solar absorbers are better for the enviroment, therefore they're better in the long run. We will eventually run out of oil and coal, as they are fossil fuels. But the sun won't stop shining for millions of years.
Answer:
Paul learns that Luis's family grows Cleopatra tangerines in their grove, and has sold the fruit to citrus packers and juice companies for forty-five years. Next, Luis takes Paul to the nursery, where the family grows trees to sell to farmers.
Explanation:
The answer is B, as it helps not only to keep the reader's attention but to also inform or persuade them more to a topic. In addition, it is also sometimes used to help convey a specific emotion, thus helping the reader get more into the text.