Final answer:
Gambling losses are the itemized deduction that is not subject to the itemized deduction phase-out, and can be claimed up to the amount of gambling winnings, regardless of income level.
Step-by-step explanation:
The itemized deduction not subject to the itemized deduction phase-out is A. gambling losses. While some itemized deductions are limited based on the taxpayer's adjusted gross income, gambling losses are deductible to the extent of gambling winnings and are not subject to the same phase-out rules.
This means that regardless of income level, gambling losses can be claimed as an itemized deduction, but only up to the amount of gambling winnings reported on your tax return. Options B (mortgage interest), C (state income tax), and D (charitable contributions) can be limited based on income levels.