A 501(c)(3) organization typically refers to a nonprofit organization that is exempt from federal income tax under the Internal Revenue Code. Among the options you provided, "a private school" is identified as a 501(c)(3) organization, as it serves a charitable purpose by providing education.
To clarify:
- A private foundation can be a 501(c)(3), but it's a specific type of nonprofit.
- A lobbying firm does not qualify as a 501(c)(3) because its primary function is to influence legislation.
- A company that donates its profits but has unrelated business income usually does not qualify as a 501(c)(3) if the unrelated business income is significant.
Thus, the correct answer is a private school.