We are told that if one believes that no one person can have an effect on society's future, then they will feel too helpless to act to change society for the better.
P: BNPEF ==> not IS (not improve society = feeling too helpless to act to change society for the better)
IS ==> not BNPEF
The stimulus then concludes that anyone who wants to improve society should reject the belief that its future will be determined entirely by vast historical forces that individuals are powerless to change.
C: IS ==> not BNPEF (do not believe that no one person can have an effect on society's future = reject belief that its future will be determined entirely by vast historical forces that individuals are powerless to change)
BNPEF ==> not IS
Answer choice (D) states: "No one who wants to improve society should accept any belief that makes him or her feel too helpless to act to change society for the better."
We can rewrite this: if one wants to improve society, they will not accept any belief that makes him or her feel too helpless to act to change society for the better.
(D): IS ==> not BNPEF BNPEF ==> not IS
As you can see, answer choice (D) merely reiterates the conclusion in the stimulus.
Therefore, the principle stated in answer choice (D), if true, would most help to justify the argument--since the conclusion would just be restating the valid principle.
Hope that helps! Please let us know if you have any other questions.
