is it safe to say that a good over and under inclusive rule is that when the verb is active the subject is sufficent and when the verb is passive the predicate is sufficient?

I understand why the last sentence is the conclusion in q5, what I'm a bit tripped up on is why the first sentence is context rather than another premise? It seems that it supports the conclusion because of the "storing food waste in their back yards" --> "shut down operations". The conclusion exists because it assumes the first sentence is wrong. Why is it context and not a premise? How can I tell the difference?