The correct answer is - something that causes people to leave their country.
A push factor is a wide term, in the sense of what can it be, so a push factor for the people to move away from their country can be safety issues, military action, economic reasons, political reasons etc. All of these factors can ''push'' a person to leave its own country, migrate to another place, and try to start fresh in the new more promising environment.
Examples:
- Push factor for the Syrians in the past few years is the waging war in their country.
- Push factor for the Balkan people to migrate to Western Europe are the economic reasons.
- Push factor from the people of North Korea to try and fled to South Korea or China is the dictatorship in the country.
