On January 1, a firm has a balance of $400 in the supplies account. During the year, the firm purchases $1,000 of supplies and records: Dr. Supplies Expense Cr. Cash 1,000 1,000 At year-end, the firm notes that they have $800 of supplies on-hand. As part of the year-end close process, the firm becomes aware that they have made a mistake in accounting for supplies. The correcting entry necessary: O Debits expense for $600 O Credits expense for $600 O Debits expense for $400 O Credits expense for $400 O No entry necessary