identify the rule that determines whether a taxpayer must include in income a refund of an amount deducted…

Brief Explanations:

The tax benefit rule determines whether a taxpayer must include in income a refund of an amount deducted in a previous year. If the taxpayer received a tax benefit from the deduction in the prior - year (such as a reduction in tax liability), the refund is generally includible in income. The tax refund rule is too general, constructive receipt deals with when income is considered received, and return of capital principle pertains to the return of an original investment, not specifically to refund of deductions.

Answer:

tax benefit rule.