C. I chose that rose for its sweet smell.
This sentence actually has two pronouns used as adjectives. The first is "that". It is an adjective because it describes which rose is being chosen. The second pronoun that's being used as an adjective is "its". "Its" tells us what the smell belongs to. Possessive pronouns are often considered possessive adjectives because they describe who or what is being owned. In this case the rose or "its" owns the smell.
