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:
J. William FRENTZ et al., Petitioners, v. COMMISSIONER OF INTERNAL REVENUE, Respondent.
No. 16946.
United States Court of Appeals Sixth Circuit.
March 7, 1967.
Arthur Clark, Jr., Cincinnati, Ohio, for petitioners, Frank E. Haddad, Jr., Louisville, Ky., on the brief.
Robert I. Waxman, Dept, of Justice, Washington, D. C., for respondent, Richard M. Roberts, Acting Asst. Atty. Gen., Lee A. Jackson, Gilbert E. Andrews, Attys., Dept, of Justice, Washington, D. C., on the brief.
Before EDWARDS, CELEBREZZE and PECK, Circuit Judges.
ORDER.
Petitioners claimed as deductions in their 1960 income tax returns their pro rata shares of losses sustained by Ken-tuckiana Broadcasting, Inc., an electing small business corporation under Sub-chapter S of the Internal Revenue Code of 1954, during the fiscal year ending October 31, 1960. The required election in the name of Kentuckiana was filed by petitioners, along with their consent as shareholders, on November 30, 1959. Kentuckiana’s charter was issued by the State of Kentucky subsequent to the purported election, and respondent disallowed the claimed deductions. From an adverse decision by the Tax Court petitioners appeal.
It being the opinion of the Court that the findings of fact by the Tax Court are not clearly erroneous, and that the ruling by the Tax Court that there must be “strict compliance” with the statutory requirements is correct,
It is ordered that the decision of the Tax Court, entered June 28, 1965, be and hereby is affirmed for the reasons set forth in Judge Bruce’s opinion, reported in 44 T.C. 485.

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