How did World War I affect the writing of Ernest Hemingway?

According to Seán Hemingway, his grandfather's war dispatches "were written in a new style of reporting that told the public about every facet of the war, especially, and most important, its effects on the common man, woman, and child." This narrative style brought to life the stories of individual lives in warfare and earned a wide readership. Before the advent of television and cable news, Hemingway brought world conflicts to life for his North American audience.

elastic potential energy

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."