Final answer:
Oregon's failure to file penalty is 5% of the unpaid tax each month, not based on AGI.
Step-by-step explanation:
The correct answer to the question of what Oregon's failure to file penalty is: c. 5% of the unpaid tax each month or part of a month the return is late. The penalty begins accruing the day after the tax filing due date and will increase up to 25% of the unpaid tax. It's important to note that this penalty is based on the unpaid tax, not your adjusted gross income (AGI).