During an accounting period, a business sells goods on credit for a total selling price of £4,000. At the start of the accounting period, there are debtors of £600. At the end of the accounting period, there are debtors of £500. What is the amount that will appear in the statement of cash flows as cash inflow from sales?

(a) £3,900

(b) £4,100

(c) £4,500

(d) £4,600