Hi there!
In literature the subject of something is basically the topic.
So if there was a story you had to read about, we'll say, a car, but they're asking what the subject/topic of the story was about, you'd say, a car, because that's what the passage is talking about.
Hope this helps! :D
Answer: B
Explanation:
Other answers don't make sense, and the theme of the passage is that recycling is more complicated than it seems.
Answer:
D
Explanation:
the comma goes before the conjunction but
