People stopped using the santa fe trail for shipping when
a. the automobile was invented.
b. stagecoach became available for public use.
c. airplanes became the primary mode used to transport goods.
d. the railroad ended shipments by caravan.

People stopped using the Santa Fe Trail for shipping when the railroad ended shipments by caravan.

d. The railroad ended shipments by caravan.

Explanation:

The Santa Fe Trail was the first commercial higway of the United States. Traders set the trail up (which was a connection between Missouri and Santa Fe, New Mexico and included about nine hundred miles of the Great Plains) during the year 1821. It stopped working because the Santa Fe railroad was completed, but until then, the Santa Fe Trail worked as a highway for many traders, pioneers and military forces of the U.S., and its role was decisive in the expansion of America to the West.

it would be  

germany had to pay all damages related to the war.

and i think

germany had to take sole responsibility for the war.