This question asks us to identify a disagreement between A and B. For them to disagree, they must both have discussed the topic they disagree about. First, let's think about what each discusses separately.
A touches on the following: recent increase in organically produced food, consumers have greater interest in env., hope for healthier planet.
B touches on: selfish motivations for buying organic, only motivated by health.
Hence, what A and B both discuss - and disagree about -seems to be related to what they think the motivation for the consumers is in now buying more organic food. With this in mind, let's check out the answer choices:
(A) is completely out of scope - present eating habits? likely that a health planet can be maintained? huh?
(B) is half out of scope - specifically, A does not talk about healthiness at all.
(C) is half out of scope too because B doesn't talk about it. Another reason it's not the answer is that this is a normative statement, whereas A and B speak descriptively (that is, they talk about what does happen rather than what should happen).
(D) looks good - it gets to the motivations and is something A would agree with and B would not. Let's keep this answer choice for now.
(E) is out of scope entirely - neither A nor B talked about persuasion.
Hence (D) is our answer.
It's important generally to recognize out of scope and half-scope answers for these kinds of questions. Make it a point when you do identify the disagreement questions to articulate for yourself a reason why *each* incorrect answer choice is incorrect.
Feel free to post if you have more questions or your own comments about this one!