unqualifying :没资格
unqualified：无条件的

"labor" is not a living thing. The term here refers to the working class or unionized sector of the economy

there's no such thing as "x received something BY y"; it would have to be "x received something FROM y"

来自谁的支持用of更合适，by是通过什么

the REAL issue, though, is "unqualifying" -- this is incorrect. "unqualifying" means "not meeting some sort of standard for qualification".
the intended meaning here is "unqualified", which means "without any sort of restriction or reservation". 无条件的

Ron： i'm loath to use apostrophe + "s" for anything but humans, animals, and the like. ‘s’更偏向一个人

The three women, liberal activists who strongly support legislation in favor of civil rights have consistently received the unqualified support of labor
强烈支持有利于民权的立法的三位女性自由活动家一直得到劳工的无条件支持

unqualifying:没资格的
unqualified：无条件的
receive support by sb（×）
receive support of sb/from sb （√）
DE改变逻辑语义，用consistent修饰名词support，而consistently本来应该修饰动词receive的

unqualifying :没资格
unqualified：无条件的

E receive support by sb用法错误，我们只能说receive support of sb/from sb
另外 DE的错误在于改变逻辑语义，因为DE用consistent修饰了support，而本来应该修饰receive的

the REAL issue, though, is "unqualifying" -- this is incorrect. "unqualifying" means "not meeting some sort of standard for qualification".
the intended meaning here is "unqualified", which means "without any sort of restriction or reservation". 无条件的

Ron： i'm loath to use apostrophe + "s" for anything but humans, animals, and the like. ‘s’更偏向一个人

unqualifying :没资格
unqualified：无条件的

unqualified: adj. 不合格的；无资格的；不胜任的；不受限制的；无条件的；绝对的
unqualifying: 不是个词

unqualifying是使没有资格，unqualified是绝对的

无条件的拥护

无条件的拥护

consistently, 持续的
根据逻辑意思，应该表达 “一直”，没有过去的含义，那就只有用 be doing

(A)(B)unqualifying使没有资格的，意思不对

①"unqualifying" means "not meeting some sort of standard for qualification".
the intended meaning here is "unqualified", which means "without any sort of restriction or reservation".
②the present participial form "are receiving" would also make sense, but remember that you aren't supposed to change the meaning of the sentence without a good reason for doing so.

unqualified无保留的/不合格的，无资格的，unqualifying无资格的，不是一个词

the issue here is just that "labor's unqualifying support" is just ridiculously awkward. this is one of those things that native speakers will understand almost instinctively, but that is nevertheless nearly impossible to explain to non-natives.

in general, i'm loath to use apostrophe + "s" for anything but humans, animals, and the like. this is definitely NOT a hard and fast rule, but i've noticed that it's fairly consistent across most usage.
thus, "an ape's vocal tract" is preferred to "the vocal tract of an ape", but "the colors of the mural" is better than "the mural's colors".

in general, if you get to pick between the apostrophe+s construction and the "of" construction, and the possessor isn't a living thing, i'd go with the latter.
but by all means try to eliminate based on other things first.

the REAL issue, though, is "unqualifying" -- this is incorrect.
"unqualifying" means "not meeting some sort of standard for qualification".
the intended meaning here is "unqualified", which means "without any sort of restriction or reservation".

--

the past perfect makes perfect (heh) sense here. the idea is that, lately, the women have been receiving support from labor.
the present participial form "are receiving" would also make sense, but remember that you aren't supposed to change the meaning of the sentence without a good reason for doing so.

unqualified=unlimited
unqualifying: 不合格的
GMAT语法中名词所有格使用要谨慎

unqualified adj. 不合格的, 无资格的 // 无限制的, 无条件的;绝对的, 十足的
unqualifying adj.没有达到要求的
A's B prefer A是一个人 e.g. Lizzy's book
by sb 形容的是动词 “support of labor" is correct, "support by labor" isn't correct