The correct option is
C At
The given preposition talks about a place.
We can determine the correct answer with the help of logic and by eliminating the incorrect answer.
Into is used to show a movement.
To is used to indicate direction, purpose, limit, attachment, comparing.
We can thus eliminate options B and C as incorrect answers.
At is used to indicate a point of time or place, state, direction. age or occupation, degree. Thus option c is the correct answer.
On is used to indicate a position on the surface and time. Hence option A is also incorrect.