Which of these excerpts from mark twain's life on the mississippi best shows twain's subtle sense of humor?
a. at last he turned up as apprentice engineer or "striker" on a steamboat. this thing shook the bottom out of all my sunday-school teachings.
b. the white town drowsing in the sunshine of a summer's morning; the streets empty, or pretty nearly so; one or two clerks sitting in front of the water street stores . .
c. the captain lifts his hand, a bell rings, the wheels stop; then they turn back, churning the water to foam, and the steamer is at rest.
d. the pilot, even in those days of trivial wages, had a princely salary—from a hundred and fifty to two hundred and fifty dollars a month, and no board to pay.