No single event or household characteristic is usually responsible for pitching people into poverty……………………………………………………….. The particular events that are most closely associated with falling into poverty vary from one region to another across the country. In some regions, irrigation system failures were found to have made a big impact; in other regions, expensive funeral feasts have ruined families.
In the third sentence, we can see that many events are mentioned. So, the sentence before it must also have a clue to the events. So, option 1 is correct.