They are sustainable by having plenty of public transport and are encouraging people to use them.

they use wind power energy and they also use alot of public transport

Mars is not a sustainable as there is no oxygen, food or water and therefore it is not sustainable. If you had to survive there you would need numurous things (how are we going to transport 4 billion people. Basic things needed are Oxygen, Food, Water and other small things like plants and animals.

Ahmedabad

Fewer cars entering central London- lower pollution emissions

Higher usage of public transport- less emissions

Will lead to more sustainable forms of transport- walking, cycling etc.

Will ease traffic congestion