Which two farming advances developed during the zhou dynasty?

1. iron plow
2. fertile silt of huang he river
3. bronze tools
4. crop rotations

Be the economy is horrible so people immigrate to the usa for a better life. most people just grow up from poverty and work day and night to support their family, some just come because there is a lot of drug dealers and gang that assaults people.

I'm sorry but there isn't a picture nor any options to pick from