The balance on the unearned rent account for Jones Co. as of 12/31 is $1,200. If Jones Co. failed to record the adjusting entry for $600 of rent earned during December, the effect on the balance sheet and income statement for December is:

A. . liabilities overstated $600; net income understated $600

B. . liabilities overstated $600; net income overstated $600

C. . liabilities understated $600; net income understated $600

D. . assets understated $600; net income overstated $600