[求助]GWD-TN-23-Q37

Q37. 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?
A.Last year the Brindon Bolt Barn’s sales volume and revenue were significantly higher than they had been the previous year.
B.The workshops and manufacturing firms that have remained open have a smaller volume of work to do this year than they did last year.
C.Soon the Brindon Bolt Barn will no longer be the only significant supplier of fasteners to Brindon
                County’s workshops.
D.The Brindon Bolt Barn’s operating expenses have not increased this year.
E.The Brindon Bolt Barn is not a company that gets the great majority of its business from customers outside Brindon
                County.

这道题答案是E，
                    但我怎么看都觉得是B，没看到这道题的讨论，希望各位大大帮我解惑，感激不尽

如果Bolt Barn的大部分收入是来自Brindon以外的城市,那么那些仍然在B城市里的公司多少不会影响bolt的收入

而E恰好否定这种情况,所以是假设.

谢谢这位大大，我搞懂了！