Cindy Smith, VP of Finance at Digital Components, Inc

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%) by randomly assigning five customers to each sales discount rate.In Cindy's experiment, "sales discount rate" is ___.

A) the dependent variable
B) a treatment variable
C) a blocking variable
D) a concomitant variable
E) a constant