The answer C Different Trains
The social problem that The Jungle by Upton Sinclair described was B.) THE LIVING AND WORKING CONDITIONS IN CHICAGO'S STOCKYARD.
Not only in the stockyard but also in the meat packing factories.
The story is about how a family intent on pursuing their American Dream was not able to do so because they became victims of corruption, wage slavery, and oppression by the capitalists in Packingtown.
