Ethan Allen and the Green Mountain Boys:a. fought intrusions by New York landlords into what became Vermont. b. were spies working for the Sons of Liberty. c. forced the British army to retreat at Concord. d. put down the revolt of the Regulators in North Carolina. e. started the colony of New Hampshire.

:a. fought intrusions by New York landlords into what became Vermont.

Explanation:

Ethan Allen and the Green Mountain Boys: fought intrusions by New York landlords into what became Vermont. The Green Mountain Boys formed by Ethan Allen were originally created to prevent New York authorities from controlling their land,their aim was to prevent the New Hampshire Grants , from becoming part of New York.

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."