Under How to position dynamic layouts topic, Clear floated layout setting there is a Knowledge check question

Could somebody explain me the answer please?

As per definition Clear floated layout ensures that the floated layout doesn't share the same horizontal space as any other floated layout before it. If we have layout A and layout B in that order, then if we clear layout A, there should be no change, as there is nothing before it?

If we clear layout B, then it would appear under layout A, because it wouldn't share the same space.

So how does clearing layout A, move layout B above it?

Thanks