Sky Company purchased supplies costing $6,000 and debited Supplies for the full amount. At the end of the accounting period, a physical count of supplies revealed $1,800 still on hand. The appropriate adjusting journal entry to be made at the end of the period would be Select one: O a. Debit Supplies, $4,200; Credit Supplies Expense, $4,200. O b. Debit Supplies Expense, $4,200; Credit Supplies, $4,200. O c. Debit Supplies Expense, $1,800; Credit Supplies, $1,800. O d. Debit Supplies, $1,800; Credit Supplies Expense, $1,800