The conclusion to be drawn from the man named shereshevskii whose abnormal brain functioning gave him virtually limitless word-for-word memory is that having memory like a video recorder.
a. him draw powerful inferences and intelligent conclusions from his vast knowledge base.
b. is an advantage because it eliminates "selective" recording (remembering some events and forgetting others), which provides no useful service to humans.
c. is largely a blessing because no event would be erased.
d. can seriously disrupt functioning in one's personal life.

d.

Explanation:

The conclusion to be drawn from the man named Shereshevskii whose abnormal brain functioning gave him virtually limitless word-for-word memory is that having memory like a video recorder can seriously disrupt functioning in one's personal life. This is mostly due to the fact that individuals like Shereshevskii are able to remember everything INCLUDING bad, stressful, and traumatic events which can drastically disrupt the quality of life of the individual.

no because it could make the world a terrible place to live in.

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."