Both the current ratio and the quick ratio for Spartan Corporation have been slowly decreasing. For the past two years, the current ratio has been 2.3-to-1 and 2.0-to-1. During the same time period, the quick ratio has decreased from 1.2-to-1 to 1.0-to-1. The disparity between the current and quick ratios can be explained by which one of the following?