The main topic of the passage is

these ‘main idea’ of a passage questions are contrived. Many people who do understand main idea very well in real life can struggle with these main idea in a passage questions. I'm a native speaker who’s taught literature, Language Arts, reading and ELL for many years and I could make an argument that it’s A or E - but both contain grammatical errors so their meaning is obscured.

The reading chosen for main idea questions is always dull and dense. Pulling out a sentence is a time consuming approach - would you go over the paragraph 12 times each time pulling out a different sentence? The other reason being - they write the answers in a deliberately confusing way.