Read the quote from Turner to the right. Which sentence is the best summary of this quotation?

“The frontier is the outer edge of the wave.”
“To the frontier the American intellect owes its striking characteristics.”

“These are the traits of the frontier.”

Hey!me its for an important test! ! which issue during the progressive era would most likely have united mary harris "mother” jones and lewis hine? a) ending child labor b) regulating monopolies c) using photography to expose poor working conditions d) exposing the lack of jobs available for untrained laborers