Boyle’s law explains the way to develop an idea and design an experiment.
the impact of gravity on the motion of objects on Earth.
the relationship between pressure and the volume of gas.
the elliptical orbit of Earth and other planets around the sun

dude you should crop your image so only the question shows. but   can you explain it better

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."

the correct answer is c.