The development of steamboats transformed trade on the Mississippi Riv

The development of steamboats transformed trade on the Mississippi River for all of the following reasons EXCEPT

A) steamboats could travel up the river against the current; in contrast, large riverboats could not travel upstream and they had to be sold for lumber when they reached their downstream destination.
B) steamboats were much faster boats than the large riverboats and could cut the travel time down the Mississippi River by two-thirds.
C) steamboats proved to be a more labor-intensive nautical mode of transportation than lumber riverboats.
D) steamboats proved to be very profitable for their operators and commercially viable for farmers sending their goods upstream and downstream on the river.

ANSWER
Answer: C