What action by muhammad in madinah made that city important to his followers?

The prophet of the fast growing islamic religion was born in the city of Madinah and the follower see the city as symbolic to the cause of the religion because they believe that god chose the city of medinah out of all other other cities in the whole world . And as such the place have a relevance that is second to none amongst the followers of the religion.

The answer should be a.

Freedom of religion, freedom of speech, being protected by our military and first responders on a daily basis and many many more.