The best answer choice would be C.
They protested the abolition of slavery.
Answer: I think the main idea is to show what struggles families faced during the Great Depression. Also, to especially show the struggled children had to face working for their families.
Explanation: Buddy Blankenship starts the paragraph by saying "I told my dad I wasn't going to school anymore". This shows that the author was a child when he started working in the mines with his father. He goes into detail on the struggle he faced, ie, "We got up at 5 in the mornin'" and "We'd work about six hours a day, seventeen hours". This kind of work is grueling and awful for a child.
The answer is A . Ancient cities that were very similar despite being 300 miles apart .
Hope this helps