How does "i sit and look out" contrast with "i hear america singing"? a. it shows a love story, whereas the other poem only discusses work. b. it uses a defined rhyme scheme, whereas the other poem is written in free verse. c. it shows the worst of america, whereas the other poem shows the best of america. d. it shows the upper class of america, whereas the other poem shows the working class.

Using the system of elimination, I'd say the correct answer is C. It shows the worst of America, whereas the other poem shows the best of America.
It's not A because there is no love being portrayed in "I Sit and Look Out;" it's not B because there is no defined rhyme scheme in that poem; it's not D because both poems show the working class. 
So based on this, it has to be C - the first poem shows hatred, pain, and violence, whereas the other one shows unity and love.