Ptarmigan Travelers had sales of $420,000 in 2016 and $480,000 in 2017. The firm's current asset accounts remained constant. Given this information, which one of the following statements must be true?

A. The total asset turnover rate increased.

B. The days' sales in receivables increased.

C. The inventory turnover rate increased.

D. The fixed asset turnover decreased.

E. The collection period decreased.