Is the underlined word in this sentence a common or proper noun?

jeffrey was excited to take a tour of the capitol in washington d. c.

a.
proper

b.
common

There is no underlined word in the sentence given above, so let me answer this question in this manner:

Proper noun indicates the exact name of a person, place or thing while common noun is the general term used to name nouns. In the sentence stated above, the proper nouns are Jeffrey, Capitol, and Washington D.C. and the common noun is tour which may either refer to educational or some other term.