The correct option is C role
Role means the function assumed or part played by a person or thing in a particular situation. Hence, Option C is correct. Among the rest of the options, ingredient means a component part or element of something, plan means a detailed proposal for doing or achieving something, platform means the declared policy of a political party or group, criterion means a principle or standard by which something may be judged or decided. These options do not express this meaning, hence incorrect.