In the context of Gunnar Myrdal's theory of regional development, which of the following are considered factors of cumulative causation?
1. Spread effects
2. Backwash effects
3. Polarization effects
4. Centripetal effects
1
1, 2, and 3 only
2
1 and 4 only
3
2 and 3 only
4
All of the above