If you are a non-profit under Internal Revenue Code sections 501(c) or 501 (d), select “Other” as your federal tax classification and then select the first option “An organization exempt from tax under section 501 (a), any IRA, or a custodial account under section 403(b)(7) if the account satisfies the requirements of section 401(f)(2)” under the “Other type” drop-down.

Please refer to the code section that states under 501(a) “An organization described in subsection (c) or (d) shall be exempt from taxation…” Therefore, by saying you are exempt under (a), you are saying that you are exempt under either (c) or (d).