I had trouble with this question and the discussion here is pretty sparse so I'll contribute what I can.
The first statement immediately presents a conditional in the form of:
1. Cultures advance ---> Independence replaces dependence;
and similarly,
2. Cultures advance ---> imposition by outsiders is replaced by initiative from within.
Notice the necessary condition for cultural advancement(what must be true in order for cultural advancement to even take place) is independence/lack of outside imposition.
It goes on to say 3. If a culture moves forward(advances) ---> natives do it.
So if cultural advancement is to occur, it must be natives, not non-natives, ushering in this advancement.
After this, it talks about how non-natives can be valuable for their advice so they are not completely worthless but are neither sufficient nor necessary for cultural advancement and any imposition by them would threaten independence and thereby threaten cultural advance( notice how both "imposition" and "threatening of independence" would serve to deny the necessary condition of our first two conditionals, thereby denying the sufficient condition, thereby failing the conditional(making it not work).
Then they substitute "cultures" for "schools", so we can replace "cultures advance" in our conditional with "schools advance".
Answer choices:
(B)- This question is not giving us a degree as to how much independence is needed. It IS needed and completely needed as it is
necessary. For this fact, we can ELIMINATE.
(C)- Out of Scope. This question fails to talk about what the whole stimulus was getting at, namely, cultural/school advancement and independence. We can only make conclusion that result from concrete information we are given, and this question is much too broad. ELIMINATE.
(D)- This choice is too strong. Participation of outsiders/non-natives does not necessarily equate to imposition and the stimulus mentions how outsiders provide valuable advice! ELIMINATE.
(E)- I originally picked this answer.
and is completely wrong for a very simple reason: it mistakes the necessary for the sufficient. It is the case that Independence ---> school/cultural advancement, it's the opposite: School/Cultural advancement ---> Independence.
In other words, independence alone does not make a school/culture advance! Rather, if a school/culture is to advance, it must have independence! It can't advance without it but just having it doesn't make it advance.
(A)- Correct answer. The ending of the stimulus states that we are trying to find a something that is the key to educational progress(school advance). What is integral to educational progress occurring; what must be in place for it to occur. Well we know School Advance ---> independence; in turn, we can conclude that A must be right because it presents the necessary condition for the sufficient condition the stimulus has provided us.
Hope this helps!