Ineed to know which continent was settled first by humans and how do i know .plzzz it's due tomorrow and i need

b. Much of the population in many areas lacks a formal education and proper job training

i know because it was first continent  to became a human habitat

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."