Answer: The part of The Proposal that showcases inner dialogue is C. Ivan's speech when Stepan leaves the room to fetch Natalya.
Step-by-step explanation: In literature, inner dialogue takes place when a character talks to himself/herself out loud or just on his/her mind and reflects on a particular issue. In The Proposal by Anton Chekhov, there is an instance of inner dialogue when Stepan leaves the room and Ivan, who is waiting for Stepan's daughter, Natalya, to propose marriage to her, starts getting nervous and trying to convince himself that Natalya is a good woman and an excellent housekeeper and that marrying her is the right thing to do since he is already 35.