Fill in the blanks with suitable prepositions:
A preposition is a word which comes before a noun or a pronoun and establishes a relationship between the elements of a clause or words. Option C)at/ in is correct as they indicate a specific time and a general time respectively. The other options are wrong as in and at can't be used in the first and second blank respectively as they indicate inside something and a specific location respectively. These uses don't fit in the given question. The correct answer is C)at/ in.