Which of the following represents one of the three types of income subject to federal taxation?

Active income represents income that is earned through services provided or work performed, such as wages, salaries, bonuses, and business income. This type of income is subject to federal taxation as it is directly tied to an individual's efforts or performance in their profession or business activities. Taxpayers report active income on their tax returns, and it is usually taxed at the individual's ordinary income tax rates.

The other options, while they pertain to different types of income, do not represent one of the primary categories typically classified under taxable income in the same direct manner as active income. Deferred income includes funds that are earned but not yet taxed, capital income refers to income generated from investments such as dividends and capital gains, and unearned income denotes income received from sources such as interest or rent. Though those types may also be subject to taxation, they are categorized differently and do not highlight the active involvement in income generation that active income signifies.