A shopkeeper says: 'Every item in my front window is on offer this week, and nothing in the front window costs more than three hundred rupees.' Which of the following could be true, but is not guaranteed to be true, on the basis of that statement alone?

The shopkeeper says every window item is on offer, not that only window items are on offer. A four-hundred-rupee shirt cannot be in the window, but it may perfectly well be on offer elsewhere in the shop - so this could be true without being forced. The second and fourth options contradict the statement outright, and the third is guaranteed by it rather than merely possible.