1.The older a city is, the more I like it.

=>C

2.The better the public transport system in a city is, the fewer people get stuck in traffic jams.

I: "best" should be "better" and "less" should be "fewer".

Sửa: The better the public transport system in a city is, the fewer people get stuck in traffic jams.

3.The farther you live from the streets, the quieter it is.

I: "quieter" should be preceded by "the".

Sửa: The farther you live from the streets, the quieter it is.

4.The more public amenities a city offers, the more convenient it is for the city's dwellers.

=>C

5.The higher the place you live in is, the less risk of flooding you face.

=>C

6.The more polluted a city is, the less attractive it becomes.

I: "fewer" should be "less".

Sửa: The more polluted a city is, the less attractive it becomes.

7.The less money you earn, the harder your life gets in the city.

I: "more hard" should be "harder".

Sửa: The less money you earn, the harder your life gets in the city.