Please correct me if I am mistaken, but are you asking about why they chose to use the word "some" in the correct answer as opposed to a stronger quantifier?
If so, the reason is because all we can know definitively is that some number of conservatives must have endorsed this liberal position. We can't conclude most or all because we do not have proof that half or more of the conservatives supported it.
However, no matter which way we slice it, it is not possible to make up 77% just from the liberal and moderate students. 24 + 51 does not add up to 77.
I hope this helps. Please let me know if you have any other questions or would like to elaborate further.
ShirnelApril 23, 2020
Yes, in the quantifier lesson @mehran stressed that it is easier to prove some than to prove all.
Thus for this question in particular looking at these two answer choices:
A: All students who labeled themselves liberal endorsed what is generally regarded as a liberal position on that set of issues.
D: Some students who labeled themselves conservative endorsed what is generally regarded as a liberal position on that set of issues.
It is easier to prove D than it is to prove A because although 77% is a larger quantity than all labeled positions mentioned; and while it could be true/true that ALL 24% who labeled themselves liberal endorsed the position. It is easier to prove and it must be true that at least 1 / SOME conservatives endorsed the position
