A hill town's tourism committee argues that listing every guest house in the town on one shared web page will raise bookings here, because the town on the next ridge did exactly that and its bookings doubled within a season. Which of the following is an assumption on which the committee's argument depends?

The whole force of the argument is that the neighbouring town's result can be carried across, and a result travels only with the condition that produced it. If bookings here are held down by a broken road rather than by ignorance of who takes guests, the listing removes an obstacle this town does not have. What the page costs is a question of affordability rather than of effect, equal traveller numbers is a far stronger claim than the argument needs, and the neighbours' goodwill is beside the point.