How does this passage reveal Upton Sinclair to be a muckraker?

Use "Excerpt from The Jungle by Upton Sinclair" to answer your question.

A.
It exposes the corrupt and dangerous practices of the meat-packing industry.

B.
It illustrates the dangers of the political machines at work in private industry.

C.
It explains how industrialization was ruining American values.

D.
It promotes the idea of taking collective action to eradicate industrial problems.

A. It exposes the corrupt and dangerous practices of the meat-packing industry.