Read this passage from "The Secret Life of Walter Mitty." "Puppy biscuit," said Walter Mitty. He stopped walking and the buildings of Waterbury rose up out of the misty courtroom and surrounded him again. A woman who was passing laughed. "He said ‘Puppy biscuit,’" she said to her companion. "That man said ‘Puppy biscuit’ to himself." What does the dialogue in the excerpt show about Mitty?
A. He is responsible and conscientious.
B. He is sour and nasty.
C. He is awkward and absent minded.
D. He is funny and entertaining.