100 POINTS PLEASE HELP ASAP!!!!
Why did it take just six weeks for a keelboat to float down the Mississippi to New Orleans but four months to make the return trip?

A. Keelboats carried a much heavier load on the return trip.
B. The return trip was upstream, against the flow of the river.
C. A keelboat's steam engine worked better with the wind than against it
D. Once the goods had been delivered to New Orleans, there was no hurry to get home.