Cindy Smith, VP of Finance at Digital Components, Inc $\mu$ ₁

Cindy Smith, VP of Finance at Digital Components, Inc.(DCI) , theorizes that the discount level offered to credit customers affects the average collection period on credit sales.Accordingly, she has designed an experiment to test her theory using four sales discount rates (0%, 2%, 4%, and 6%) .First, she classified DCI's credit customers into three categories by total assets (small, medium, and large) .Then, she randomly assigned four customers from each category to a sales discount rate.Cindy's null hypothesis is ___.

A) $\mu$ ₁ $\neq$$\mu$ ₂ $\neq$$\mu$ ₃ $\neq$$\mu$ ₄
B) $\mu$ ₁ $\ge$$\mu$ ₂ $\ge$$\mu$ ₃ $\ge$ $\mu$ ₄
C) $\mu$ ₁= $\mu$ ₂= $\mu$ ₃= $\mu$ ₄
D) $\mu$ ₁ $\le$$\mu$ ₂ $\le$$\mu$ ₃ $\le$$\mu$ ₄
E) $\mu$ ₁ $\le$$\mu$ ₂ ≥ $\mu$ ₃ $\le$$\mu$ ₄