Grim Grinders began the year with a $3,500 credit balance in its allowances for doubtful accounts. During the year it accrued $22,000 of bad debt expense and wrote off accounts totaling $27,000. At year-end, a percentage of the outstanding accounts receivable indicated that a $4,500 allowance should be provided for on that date. The year-end adjustment for bad debt expense should be

a.	$1,000
b.	$4,500
c.	$5,000
d.	$6,000

Please explain the answer.