What was upton sinclair’s main purpose in writing the jungle?
to promote the socialist views that he adopted as an adult
to explain why journalists had an obligation to tell the truth
to arouse public sympathy for slaughterhouse workers
to prompt congress to pass food-safety laws

To arouse public sympathy for slaughterhouse workers.

Explanation:

When he wrote The Jungle, Upton Sinclair wanted to arouse public sympathy for slaughterhouse workers. These workers were often immigrants who earned very little money, worked long hours and faced particularly bad working conditions. However, his work did cause an outrage, but due to the unsanitary conditions that were described in slaughterhouses, and the bad quality of the meat being produced there.