Which branch of the U. S. government has the power to form an army and navy?

The Congress have the power raise an army or navy.

Explanation:

hopefully im right the United States Department of Defense and Congress have the power or simply the Executive Branch Department.

hope i helped

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 : -/