The picture shown suggests that the united states

a) should stop sinking enemy passenger ships.
b) does not need to get involved in european affairs.
c) will have its patience rewarded for staying out of war.
d) needs to prevent german u-boats from doing further harm.

The correct answer is D) needs to prevent German U-boats from doing future harm.

The picture shown suggests that the United States needs to prevent German U-boats from doing future harm.

The cartoon is referring to the sinking of the U.S. boat Lusitania that was attacked by the Germans in World War 1.

On May 7, 195, a German U-boat attacked the U.S. boat Lusitania and sank it.  Nearly 1,100 people died in the incident. That was one of the reasons why the United States entered World War 1. That is why the cartoon is representing, that the United States needed to prevent German U-boats from doing future harm.

it refers to race, i am pretty sure this was a popular term in nazi germany or something.