GMAT Critical Reasoning (CR) | Re: Assumption-- Singing in the rain umbrella

Singing in the Rain Umbrella Corp. plans to institute a marketing campaign in
which it sells umbrellas at the exits of subway stations during rainy weather. The
umbrellas will be sold at a price that is slightly higher than normal.The company
thinks the sales of these higher - priced umbrellas will be greater than normal
sales of umbrellas, because the purchasers of these umbrellas will be forced to
buythem if they do not want to get wet.

IT assumes that
1> Passengers of subway stations