Choice "C" is correct. Factoring receivables is the process by which a company converts its receivables to cash by assigning them to a factor, either with or without recourse.
Choice "b" is incorrect. The fact that the receivables have been recorded implies that the company has already sent invoices to its customers setting the payment due date. Generally, the due date cannot be changed after the invoice has been sent, nor is changing the due date likely to speed up the overall customer payment rate.
Choice "a" is incorrect. Discounting is the process of converting notes receivable, not accounts receivable, to cash.
Choice "d" is incorrect. Demanding payment from customers before the due date is likely to anger customers, but is not likely to speed up the overall customer payment rate. The invoice sets the payment terms of the receivable.