Answer:
providing conversations between Hughie and Trevor.
Step-by-step explanation:
'The Model Millionaire' is a short story written by Oscar Wilde. The story is about Hughie Erskine, a good-looking man who is unsuccessful in his life.
The technique that Wilde has used to characterize Hughie and Trevor's characters is through their conversation. The readers get to know the character traits of Hughie and Trevor through the conversation between them. The readers get to know that Hughie, though is unemployed but is generous when he told Trevor about his charity to the old man. And Trevor's characterization is also revealed through his conversation with Hughie.
Therefore, option C (providing conversations between Hughie and Trevor) is correct.