Studies in elementary schools have shown that introverted children act

I think it's E. OA?

My rationale:

Question asks us to gauge the effectiveness of the "touch and go" method. The touch and go method states that introverted children crave attention up to a certain limit. I assume that we are looking for a question which helps us gauge the effectiveness of this technique for satisfying attention craving without going over the attention limit

A - Irrelevant. Whether or not more effective methods exist doesn't impact how effective the "touch and go" method might be
B - Might be OK. If children crave attention more from one party than another, then maybe the "touch and go" method wouldn't satisfy the child's craving for attention if the child values attention from classmates more.
C - Irrelevant. Introverted children are shown to behave a certain way. Reading does not mention impact of awareness.
D - Irrelevant. Parents appreciating the use of the "touch and go" technique doesn't change effectiveness
E - Might be OK. If because of the teacher's praise, the classmates end up showering attention on the student, then that shows an unintended consequence not contemplated by child psychologists, and would make the technique ineffective.

Between B and E, I think E is the stronger choice. The reading doesn't distinguish between different kinds of attention, and seems to treat all attention as the same. B would require a few follow up questions in order to gauge effectiveness. For example, if we found out that children craved attention more from fellow classmates, we would have to ask how much more, and find a way to quantify the relative value of attention from each party in order to understand whether the technique is effective. E on the other hand is very straight-forward. If we found out that classmates end up showering the student with attention, which is precisely what the "touch-and-go" method tries to avoid, then we will have determined effectiveness.