can you solve step by step please ?

The unadjusted trial balance for a company as of Dec 31, 2020 appears below. Debit Credit Cash $10,000 Accounts receivable 12,000 Inventory 15,000 Prepaid insurance 4,800 Equipment 9,000 Accumulated depreciation $3,600 Accounts payable 1,000 Unearned revenue 9,400 Common stock 22,000 Retained earnings 7,500 Dividends 1,000 Revenue 28,600 Salary expense 8,200 Supplies expense 1.500 Utility expense 800 Rent expense 3,600 Advertising expense 1,200 Cost of goods sold 5,000 $72,100 $72,100 Additional data: (A) Accrued salaries on December 31, 2013 amount to $600. (B) of the amount in unearned revenue, $5,500 had still not been earned at year-end. (C) The equipment was purchased on January 1, 2018. It is being depreciated over a 5 year life using the straight line method of depreciation with no salvage value. (D) The prepaid insurance account reflects the annual premium which was paid on October 1, 2020, Additional data: (A) Accrued salaries on December 31, 2013 amount to $600. (B) of the amount in unearned revenue, $5,500 had still not been earned at year-end. (C) The equipment was purchased on January 1, 2018. It is being depreciated over a 5 year life using the straight line method of depreciation with no salvage value. (D) The prepaid insurance account reflects the annual premium which was paid on October 1, 2020. The adjustment to record item (B) above would include a decrease to: Select one: a. revenue for $5,500 b. revenue for $3,900 O c. unearned revenue for $5,500 Od, unearned revenue for $3,900 e, cash for $3,900