A researcher wants to measure the effect that watching a documentary about climate change has on a subject’s attitudes toward "green" practices. What would be the most appropriate research method?

Conducting An Experiment

Explanation:

The most appropriate research method will definitely be "conducting an experiment".

In as much as the researcher wants to find out the effect of watching a documentary about climate change on a subject’s attitudes toward "green" practices, he can only achieve that by conducting an experiment.

The experiment carried out will provide an evidence on which he can draw conclusions for or against the hypothesis. The experiment conducted will provide a basis for final assessment, judgment and conclusion.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )

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."