After a dog has been conditioned to salivate to the sight of a triangle, the triangle alone was presented to the dog every three minutes. Over the course of several trials, the amount of saliva secreted by the dog in response to the triangle decreased to zero. At that point, the dog was put back in his cage for the night. What happened the next morning when the triangle was presented to the dog again

world war i had a devastating effect on german-americans and their cultural heritage. up until that point   german-americans, as a group, had been spared much of the discrimination, abuse, rejection, collective mistrust experienced by so many different racial and ethnic groups in the history of the united states. indeed, over the years, they had been viewed as a well integrated and esteemed part of american society. all of this change with the outbreak of war.  

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."

answer; occurs if the conflict is recognized logically and intellectualized;