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 appellant. 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:
UNITED STATES v. METCALF et al. In re F. P. NEWPORT CORPORATION, LIMITED.
No. 11059.
Circuit Court of Appeals, Ninth Circuit.
Feb. 18, 1946.
Rehearing Denied March 21, 1946.
Samuel O. Clark, Jr., Asst. Atty. Gen., Sewall Key, A. F. Prescott, Louise Foster, and Harold C. Wilkenfeld, Sp. Assts. to Atty. Gen., and Charles H. Carr, U. S. Atty., E. H. Mitchell, Asst. U. S. Atty., and Eugene Harpole, Sp. Atty., BIR., all of Los Angeles, Cal., for appellant.
Bailie, Turner & Lake, of Los Angeles, Cal., for appellee H. F. Metcalf.
Before GARRECHT, MATHEWS and PIEALY, Circuit Judges.
See In re F. P. Newport Corp., 9 Cir., 93 F.2d 630; Id., 9 Cir., 97 F.2d 504; Id., 9 Cir., 98 F.2d 453; City of Long Beach v. Metcalf, 9 Cir., 103 F.2d 483; Security-First National Bank v. Bank of America National Trust & Savings Assn., 9 Cir., 111 F.2d 50; United States v. Met-calf, 9 Cir., 131 F.2d 677; Security-First National Bank v. United States, 9 Cir., 153 F.2d 563.
MATHEWS, Circuit Judge.
In Security-First National Bank v. United States, 9 Cir., 153 F.2d 563, we affirmed an order which, on February 6, 1945, affirmed an order of a referee in bankruptcy-which, on June 6, 1944, directed H. F. Met-calf, trustee in bankruptcy of the estate of F. P. Newport Corporation, Limited, bankrupt, to pay a claim of the United States, appellant here, for income taxes ($19,-363.65, plus interest) assessed against the trustee for the calendar years 1938 and 1939. The taxes were assessed on income-(rents and royalties) received by the trustee from the trust property mentioned in. Security-First National Bank v. United States, supra. The order of June 6, 1944, directed the trustee to pay appellant’s claim: out of income received or to be received: from the trust property.
The trustee did not obey the order of June 6, 1944. Instead, he applied for and, on October 17, 1944, obtained from the referee an order directing him to pay Security-First National Bank of Los Angeles, a secured creditor of the bankrupt, $5,264.11 out of income received from the trust property — income on which taxes were then, and are now, due and owing to appellant. The court affirmed the order of October 17, 1944, by an order entered on April 13, 1945. From the order of April 13, 1945, appellant has appealed.
As indicated above, the order of October 17, 1944, in effect, directed that, before paying taxes on income received by him from the trust property, the trustee should pay the bank $5,264.11 out of such income. Thus, in effect, it was held that the bank’s right in and to such income was superior to appellant’s right to taxes thereon. We have held otherwise. The order of October 17, 1944, should not have been applied for, granted or affirmed.
The order of April 13, 1945, here appealed from, is reversed.
See Security-First National Bank v. United States, supra.
See Security-First National Bank v. United States, supra.

Question: This question concerns the first listed appellant. 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