If you went door-to-door with a petition trying to get enough signatures for a proposal to be voted on by citizens, what form of direct democracy would you be engaging in

It would be called "Initiative".

The main purpose behind the Initiative processes is problem solving which come up in many democracies of the nations which vary from the common interest of the general population and which cannot be solved by elections.

unknown. best bet to watch it is at kissanime (a lot of popups and has ads and has potential to be a virus not recommended) or crunchyroll (recommended but has ads and has no popups). you will have to wait. i really want netflix to give the other seasons.

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."