is the printmaking process that is based on the observation that grease and water will not mix. A. Silkscreen
B. Mezzotint
C. Etching
D. Lithography

Lithography is the printmaking process that is based on the observation that grease and water will not mix.

its d i know cause i've been googling it

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."