Rich, very rich, poor, very poor, and because working in major cities have higher incomes in rural areas makes it possible for people to work in the city.
The rich are very rich and very poor. And because it works in the big cities have higher incomes in rural areas. Make people move into work in the city.
The rich are very rich and poor is very poor. And because of working in a big city income is higher than in the countryside. Make someone moving in to work in the city.