If the opening balance of rent accrued at the beginning of the year was$1,000, rent expense for the year was$20,000 and the closing balance of rent accrued at the end of the year was$1,200 the amount paid in cash for rent during the yearis:

A.20200 B.21000 C. 19800 D.22200

I think opening balance+rent expense-cash=closing balance so I choose C but Im not sure whether it is correct.Please explain it in detail.