Answer:
The answer is a. is an estimate of the length of time the receivables have been outstanding.
Explanation:
Days' sales in receivable is calculated as Average sales receivable / total credit sales in the period x number of the in the period.
The ratio is used to measure how long (in days) it takes for a firm to collect its sales receivable based on its past collection performance.
Thus, a is chosen.
The definition in b is referred to Receivable Turnover, thus it is not chosen.
For c. The formula given is wrong, thus it is not chosen.
