Assuming unearned revenues are originally recorded in balance sheet accounts,the adjusting entry to record earning of unearned revenue is:

A) Increase an expense; increase a liability.
B) Increase an asset; increase revenue.
C) Decrease a liability; increase revenue.
D) Increase an expense; decrease an asset.
E) Increase an expense; decrease a liability.

The adjusting entry to record earning of unearned revenue would decrease the liability account (unearned revenue) and increase the revenue account. This is because unearned revenue represents an obligation to perform a service or deliver goods, and as the service or goods are provided, the obligation decreases and revenue is earned. Therefore, the correct choice is C) Decrease a liability; increase revenue.