The convoy system, instituted in may 1917,
a. had failed by november 1917.
b. eliminated the sinking of allied ships.
c. ended the war.
d. cut merchant marine losses greatly.

d. cut merchant marine losses greatly.

Explanation:

In 1917, Germany unleashed an unrestricted submarine war around the waters of Europe, which would bring the United States into the war.

Allied losses totaled more than 2.7 million tons. Nevertheless, the effort was not enough to beat the allies who had adopted a more efficient train system against the U-Boot; With it, about 2 million US soldiers were transported to the front, as well as weapons and supplies from Europe.

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explanation: