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