Smart Touch uses the allowance method to account for bad debts. At the beginning of the year, Allowance for doubtful debts had a credit balance of $2 200. During the year you recorded Bad debts expense of $6 000 and wrote off uncollectable receivables of $4 200. What is the year-end balance in Allowance for doubtful debts? Select one: a. $4,000 O b. $6 200 c. $6 400 O d. $2.000