What follows is an opinion from a United States Court of Appeals.
Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
When coding the detailed nature of participants, use your personal knowledge about the participants, if you are completely confident of the accuracy of your knowledge, even if the specific information is not in the opinion. For example, if "IBM" is listed as the appellant it could be classified as "clearly national or international in scope" even if the opinion did not indicate the scope of the business. 

Your task concerns the first listed respondent. The nature of this litigant falls into the category "federal government (including DC)", specifically "other agency, beginning with "F" thru "N"". Your task is to determine which specific federal government agency best describes this litigant.

Opinion:
Wilfred C. RICE and Martha J. Rice, Plaintiffs-Appellants, v. COMMISSIONER OF INTERNAL REVENUE, Defendant-Appellee.
No. 77-1093.
United States Court of Appeals, Sixth Circuit.
March 22, 1978.
Wilfred C. Rice, Detroit, Mich., for plaintiffs-appellants.
Myron C. Baum, Acting Asst. Atty. Gen., Gilbert E. Andrews, Gary R. Allen, Philip I. Brennan, Tax Div. U. S. Dept, of Justice, Mead Whitaker, Chief Counsel, Internal Revenue Service, Washington, D. C., for defendant-appellee.
ORDER
BEFORE EDWARDS, ENGEL and MERRITT, Circuit Judges.
Taxpayers appeal from a judgment of the Tax Court dismissing taxpayers’ petition for redetermination of deficiency. The Tax Court dismissed on grounds that the petition was mailed one day later under 26 U.S.C. § 6213, which provides:
“Within 90 days . . . after notice of deficiency authorized in § 6212 is mailed . . the taxpayer may file a petition with the Tax Court for a redeter-mination of the deficiency.” (Emphasis added.)
The notice of deficiency to taxpayers was dated and mailed on April 30, 1976, and taxpayers’ petition for redetermination of deficiency was mailed on July 30, 1976, one day late under the statute. Therefore, the Tax Court ruled that it was without jurisdiction to redetermine the deficiency and we affirm. See Gradsky v. Commissioner of Internal Revenue, 218 F.2d 703 (6th Cir. 1954); DiViaio v. Commissioner of Internal Revenue, 176 U.S. App.D.C. 229, 232, 539 F.2d 231, 234 (1976). While the strict application of the 90-day rule may appear harsh on the surface, we should point out that taxpayers had an alternate means of challenging the Commissioner’s determination by paying the assessment and then suing for refund in the appropriate district court under 26 U.S.C. § 7422.
While we understand taxpayers’ argument that the best evidence of the date of mailing of the notice of deficiency would be the postmarked letter, that evidence, if it still exists, is solely within the control and possession of taxpayers and is not part of the record. The Commissioner has offered the next best evidence of mailing, namely, two receipts for certified mail bearing the date April 30, 1976.
On the basis of our review of the briefs and the record on appeal we therefore find that the issue below is unsubstantial and does not require oral argument. Rule 9, Rules of the United States Court of Appeals for the Sixth Circuit. Accordingly, it is ordered that the judgment of the Tax Court is hereby affirmed.

Question: This question concerns the first listed respondent. The nature of this litigant falls into the category "federal government (including DC)", specifically "other agency, beginning with "F" thru "N"". Which specific federal government agency best describes this litigant?

Choices:
Food & Drug Administration
General Services Administration
Government Accounting Office (GAO)
Health Care Financing Administration
Immigration & Naturalization Service (includes border patrol)
Internal Revenue Service (IRS)
Interstate Commerce Commission
Merit Systems Protection Board
National Credit Union Association
National Labor Relations Board
Nuclear Regulatory Commission

Answer: 5