Question

what was upton sinclairs 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

Explanation:

Upton Sinclair wrote The Jungle to expose the harsh working conditions in the meat - packing industry. While it did have an impact on food - safety laws (a secondary effect), his primary focus was on the workers. He was a muckraker, and his main intent was to arouse public sympathy for the exploited slaughterhouse workers. Promoting socialist views was not the main purpose of this particular work in the context of its immediate impact on public perception of the workers' plight. Explaining journalists' obligation to tell the truth was not the core aim. And while food - safety laws came later as a result of public outcry (which the book contributed to), the main focus was on the workers.

Answer:

to arouse public sympathy for slaughterhouse workers