Which of the following is a valid tax deduction?

Mortgage interest payments are a valid tax deduction because they are typically considered an essential expense for homeowners. In the United States, the tax code allows for the deduction of interest paid on a mortgage for your primary residence, which can significantly reduce taxable income. This deduction incentivizes homeownership and supports individuals in financing their homes, making it a common and beneficial deduction for many taxpayers.

Other options mentioned, such as costs related to plastic surgery, political contributions, and commuting expenses, do not qualify as valid tax deductions under most circumstances. Costs for plastic surgery are generally personal expenses and not deductible unless the surgery is deemed medically necessary. Political contributions are not deductible as they are considered donations made to support electoral candidates or political causes. Commuting expenses, typically the daily travel between home and work, are also not deductible as they are regarded as personal commuting costs rather than business expenses.