Read the following excerpt from "1 Sell a Dog' by Mark Twain:
The General looked even more surprised than before, and for a moment he couldn't seem to find his voice: then he said, "Do you mean to tell me that you were selling another man's dog-and knew it?" What is the role of the idiom in this sentence?

A. To communicate the General's anger at being duped by Twain
B. To include a line of dialogue that makes the scene more lifelike
C. To show that the General had a difficult time eaying something
D. To inject humor by showing that the General had developed laryngitis
HELP PLEASE​