Mr. Smith did not pay his full credit card balance on June 5th, the due date each month for payment. The unpaid balance was $800. He purchased a new washing machine on credit on June 30 for $1,000. If interest is charged at a rate of 18%, compounded daily, what would be the interest charge on his next credit card bill using the average daily balance method?

a) $26.63

b) $21.77

c) $14.79

d) $13.32