Select the most appropriate option that can substitute the underlined segment in the given sentence.

Our office is in the $$2^{nd}$$ floor of the skyscraper.

A

is for the $$2^{nd}$$ floor

B

is with the $$2^{nd}$$ floor

C

is at the $$2^{nd}$$ floor

D

is on the $$2^{nd}$$ floor