The given sentence is
I live (in/at) Ambala (in/at) Harayana (in/at) India.
Ambala is a town in the state of Harayna which is in India (country). You can replace the place names with anything familiar for understanding.
My English teacher and my mother argued that the answer is 'at,in,in'. They said that because these blanks are successive, and Ambala is smaller as compared to a state and a country that are in the same sentence, 'at' will be used for Ambala.
My argument was that the correct answer should be 'in/in/in'. This mainly comes from intuition from reading lots of novels. If I had to say a reason, it would be that all three are big enough places and successive use of in/at doesn't make any difference.
I need a third informed opinion. Thanks.