Gerallt,
Alistair makes a great point in his initial reply that I whole-heartedly agree with - the idea of flipping the question in order to rule out possible incorrect answers. Using this technique, which I also used on my PMP efforts, changes the question into a positive inquiry, "Which statements do apply to stories?" Looking at the answers again in light of this inversion technique makes the in/correct answers much more visible. Stories are A, C & D ... but not B (according to the PMI-ACP blue sky / green sky perspective). When in doubt go with the, "What would PMI do?" just like on the PMP exam and you should be fine.
All the best,
Patrick