Answer:
Sinclair presented his ideas by writing on the themes of oppression, capitalism, poverty, and socialism.
Step-by-step explanation:
Upton Sinclair was a renowned American writer of his time who wrote almost 100 books in different genres. Of all his work, Sinclair most famous 'The Jungle' was something where he exposed the poor conditions in the US meatpacking industry. Apart from this, in his another book 'The Brass Check', Sinclair exposed an American journalism for illegally presenting news without any proper research.
Sinclair always made sure to present before his readers the harsh realities of the happenings in US. Be it poverty or capitalism or oppression or anything, exposing wrong people involved in wrong doings was something he always wrote about.