Dr. mientka designs an experiment. he randomly assigns his participants to 2 groups, pretests them on general intelligence, and then proceeds with his treatment (one group participates in a self-esteem-building program, and the other group participates in a resiliency/self-regulation-building program). these programs take 6 months to run. then he posttests the participants in each group with the same test that was his pretest. during the 6-month programs, 17 of his participants leave the study for a variety of reasons. this means that dr. mientka's results might be affected by:

Most likely: internal validity (or lack of sufficient evidence).

Explanation:

It really depends on what the hypothesis that Dr. Mentika's originally created. But, in general, it is known that behavioral psychology experiments are held with smaller focus groups. Nonetheless, we could also say that, depending on which group they abandon, the answer could also be: external validity.

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."