Question

Which of these excerpts from Carl Sandburg's "Three Boys with Jugs of Molasses and Secret Ambitions" uses repetition?

Answer 1

#3 They went to the railroad stations and bought tickets for the fast trains and the slow trains and even the trains that back up and run backward instead of where they start to go.

Answer 2

I believe the correct answer is 3) They went to the railroad stations and bought tickets for the fast trains and the slow trains and even the trains that back up and run backward instead of where they start to go. 
Repetition refers to when you repeat certain words and phrases in a particular sentence or paragraph. This is the only sentence where something is repeated, and that is the word trains.