The process of discrimination allows one to react in different ways to similar stimuli.

That statement is true

The process of discrimination would make people react differently to similar stimuli because they develop an underlying negative perception toward the stimuli.

For example, let's say that we are constantly taught that the member from a certain race group is inherently bad. When ever we see an innocent person that belong to that race group, we might automatically made an assumption that that person might do something bad without having any single proof.

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."