What is the source of exemption from gift tax among the following?

The correct answer for the source of exemption from gift tax is a direct medical payment. Under the IRS rules, payments made directly to medical institutions for someone's medical expenses are exempt from gift tax. This is because the IRS allows individuals to pay for others' medical expenses without it counting against the annual gift tax exclusion limit, as long as the payment is made directly to the provider of medical services.

In the context of gift tax exemptions, each of the other options does not align with the stipulations for specific tax exemptions. Gifts made to a spouse generally qualify for marital deduction but have conditions associated with it. The annual exclusion applies to gifts, but for a dependent, the exclusion does not give any additional exemption. Lastly, gifts made to qualified charities are generally deductible, but they are categorized differently in terms of how they affect an individual's overall tax liability rather than serving as a direct exemption from gift tax itself.

Therefore, the direct medical payment is clearly stated within the tax regulations as a distinct exemption, making it the source of exemption from gift tax among the provided choices.