What does an increase in accounts receivable (trade debtors) days likely indicate?

I. the use of more liberal selling terms to promote sales

II. increase competitive pressures in the marketplace

III. A tightening of purchase terms by trade suppliers

IV. More stringent selling terms due to increase competitive pressures

(which one?)

a. I and II only

b. II and III only

c. I and IV only

d. II and IV only