Which landforms do you think are best for farming in north america? why?

It depends greatly on what you're farming

Explanation:

I'd say for beef livestock the warmer more flat lands are the most common spot. For Dairy livestock and small livestock it's more common for them to be in cooler more mountain filled areas. As for farming with plants I'm not as familiar with that.

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."