3. B Overcrowded areas make the lives pf people becomes more difficult.

4. B Although big cities offer doog standards of living, people also have to facec problems such as traffic jam or pollution.\

5. C Did you find ut any solutions to reduce crimes in Manila?

Ex9: 

1. C The more overcrowded cities get, the more problems prople face.

2. C The people who are living in dederted house are very poor.

3. B This is the first time I have ever been to Brazil.

4. A iy is very pleasant to living in the countryside.

Mình trình bày trong hình nhé >~<