The Rule for Converting Credit Sales to Cash Received from Debtors

The rule for converting credit sales to cash received from debtors is:

A) income - accounts receivable at the beginning + accounts receivable at the end = cash received.
B) income + accounts receivable at the beginning - accounts receivable at the end = cash received.
C) income + or - accounts receivable at the beginning + or - accounts receivable at the end = cash received.
D) none of the above.