Settlers along the ohio and mississippi rivers use these waterways

balearic sea - is a body of water in the mediterranean sea around the balearic islands. baltic sea - is a mediterranean sea of the atlantic which is enclosed by scandinavian and baltic countries. barents sea - is a marginal sea in the artic ocean located off the northern coast of norway and russia.

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."