On September 15, 2021, Harriet sold a vehicle she had initially purchased in January 2018 for use in her business. This was the only asset she purchased that year, and she elected not to claim the Section 179 deduction or the special depreciation allowance. Harriet used the vehicle 100% for business purposes each year that she owned it. What convention will she use to figure her depreciation deduction for the year of sale?

Half-year.

Mid-month.

Mid-quarter.

Short-year.