The profitability of a business is reduced by anything that undermines ... ...

The profitability of a business is reduced by anything that undermines employee morale. This is why paying senior staff with stock options, which allows them to earn more when the enterprise prospers, is not a wise policy because it increases dramatically the difference in income between senior staff and employees who are paid only a fixed salary. Which one of the following is an assumption on which the argument depends?
(A) Large income differences between fixed-salary employees and senior staff tend to undermine employee morale.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Oct 2012 LSAT (PT67): Logical Reasoning A