As with just about everything in aviation there can be more than one correct answer to a specific question. The beak is correct in saying that spanwise flow, defined
as flow that travels along the span of the wing from the root to the tip, more or less parallel to the leading edge, is altered. However chordwise flow is altered to a greater extent as the spoiler dumps lift by creating a controlled stall in that part of the wing directly behind it.
Since a stalled or partially stalled airfoil is most commonly linked to chordwise flow I would go with A.