In Brindon County, virtually all of the fasteners-such as nuts, bolts, and screws-used by workshops and manufacturing firms have for several years been supplied by the Brindon Bolt Barn, a specialist wholesaler. In recent months many of Brindon County's workshops and manufacturing firms have closed down, and no new ones have opened. Therefore, the Brindon Bolt Barn will undoubtedly show a sharp decline in sales volume and revenue for this year as compared to last year.

The argument depends on assuming which of the following?

【选项】The Brindon Bolt Barn's operating expenses have not increased this year.