Who was the youngest ever president?

The youngest person to assume the presidency was Theodore Roosevelt, who, at the age of 42, succeeded to the office after the assassination of William McKinley. The youngest to become president by election was John F. Kennedy, who was inaugurated at age 43.

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."