What guarantees a person must be given the chance to defend himself or herself in court?

The Sixth Amendment of the U.S Constitution guarantees that a person must be given the chance to defend him/herself in court. Under this amendment, every person has a right to a public trial without unnecessary delay, the right to a lawyer, an impartial jury, the right to know who are the accusers, and what is it that person is being accused of.

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."