Could you tell me why?

Anybody explain me the reasons?
THANKS!!

30.Satre believed {each individual is responsible to choose one course of action over another one,} that it is the choice that gives value to the act, and that nothing that is not acted upon has value.
(A) each individual is responsible to choose one course of action over another one
(B) that each individual is responsible for choosing one course of action over another
(C) that each individual is responsible, choosing one course of action over another
(D) that each individual is responsible to choose one course of action over the other
(E) each individual is responsible for choose one course of action over other ones
A):B       [Part E COMPLEMENTATION]
31.Although the Supreme Court ruled as long ago as 1880 that Blacks could not be excluded outright from jury service, nearly a century of case-by-case adjudication {has been necessary to develop and enforce the principle that all Juries must be} drawn from “a fair cross section of the community.”
(A) has been necessary to develop and enforce the principle that all Juries must be
(B) was necessary for developing and enforcing the principle of all juries being
(C) was to be necessary in developing and enforcing the principle of all juries to be
(D) is necessary to develop and enforce the principle that all juries must be
(E) will be necessary for developing and enforcing the principle that all juries being
A):A       [Part E COMPLEMENTATION]
32.{The first balloon passengers were a sheep, a duck, and a rooster that were ascended} from Versailles, France, in a basket beneath a hot-air balloon in September 1783.
(A) The first balloon passengers were a sheep, a duck, and a rooster that were ascended
(B) The first balloon passengers were a sheep, a duck, and a rooster that ascended
(C) A sheep, a duck, and a rooster were the first balloon passengers that ascended
(D) A sheep, a duck, and a rooster that were the first balloon passengers to ascend
(E) A sheep, a duck, and a rooster were the first balloon passengers ascending
A):B       [Part E COMPLEMENTATION]
33.Amelie Carrefour worked continuously through the 1860s and early 1870s with the painter Pierre-Auguste Renoir, since there are very few signed works of hers, the {inescapable conclusion seems to be one of Carrefour conceiving and executing part of Renoir’s enormous production of that period.}
(A)inescapable conclusion seems to be one of Carrefour conceiving and executing part of Renoir’s enormous production of that period.
(B)conclusion of Carrefour conceiving and executing part of Renoir’s enormous production of that period seems inescapable
(C)conclusion seems to inescapable that part of of Renoir’s enormous production of that period was conceived and executed by Carrefour.
(D)conclusion of part of Renoir’s enormous production of that period having been conceived and executed by Carrefour seems inescapable
(E)seemingly inescapable conclusion is that Carrefour would have conceived and executed part of Renoir’s enormous production of that period.
A):C          [TEST 4 SEC.1]
34.{Based on the birth rates of African countries such as} Tanzania and Namibia, scientists estimate that this continent will face serious problems of overpopulation and starvation in 20 years.
(A) Based on the birth rates of African countries such as
(B) On the basis of birth rates of African countries such as
(C) Based on the birth rates of African countries like
(D) On the basis of birth rates of African countries, like those of
(E) Based on such birth rates as those of African countries like
A):B          [TEST 4 SEC.1]
35.{He was a polio victim and Greg Burke} developed into one of the greatest athletes of his time.
(A) He was a polio victim and Greg Burke
(B) A polio victim, Greg Burke
(C) Polio victim that he wasand Greg Burke
(D) Greg Burke has been a polio victim, and she
(E) Being a polio victim, Greg Burke
A):B          [TEST 4 SEC.1]
36.Psychics and astrologers are to the post-modern 1990s {just like an enlightened monk and guru was} to an earlier time.
(A) just like an enlightened monk and guru was
(B) as have been an enlightened monk and guru
(C) what enlightened monks and gurus were
(D) what enlightened monks and gurus are
(E) just the same as enlightened monks and gurus had been
A):C          [TEST 1 SEC.3]