Layla has not been interested in even her favorite activities for several weeks. She has trouble sleeping and concentrating. She has also felt very hopeless about the future. Layla may be experiencing

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."

you answered your own : -/