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)". Your task is to determine which category of federal government agencies and activities best describes this litigant.

Opinion:
In the Matter of the Application of Harry VISSERING.
Court of Appeals of District of Columbia.
Submitted January 11, 1928.
Decided March 5, 1928.
No. 2006.
Appeal from the Commissioner of Patents.
H. H. Benjamin, of Chicago, Ill., and J. T. Basseehes, of New York City, for appellant.
T. A. Hostetler, of Washington, D. C., for Com’r of Patents.
Before MARTIN, Chief Justice; VAN ORSDEL, Associate Justice; and SMITH, Judge of the United States Court of Customs Appeals.
VAN ORSDEL, Associate Justice.
This appeal is from the Commissioner of Patents rejecting appellant’s application for a patent for a car brake step described in the following claim: “1. A brake step adapted to be secured to a car body and having a shelf portion adapted to act as a rest for the foot and provided with an abutment portion comprising a plurality of continuous spaced pressed portions.”
The step is Z-shaped in cross section, and supported by V-shaped brackets. It is made of pressed sheet metal provided with corrugations on the upper surface to prevent the user from slipping.
In the opinions of the tribunals of the Patent Office, the construction upon which the patent is sought is clearly pointed out in three references relied upon, and from an examination of the prior art we agree with the Commissioner “that applicant has done no more than pick out one feature from one patent, another from another, and so on, and unite them in a single structure. The step possesses no new or improved function as a result of such assemblage of old features.”
The decision of the Commissioner is affirmed.

Question: This question concerns the first listed appellant. The nature of this litigant falls into the category "federal government (including DC)". Which category of federal government agencies and activities best describes this litigant?

Choices:
cabinet level department
courts or legislative
agency whose first word is "federal"
other agency, beginning with "A" thru "E"
other agency, beginning with "F" thru "N"
other agency, beginning with "O" thru "R"
other agency, beginning with "S" thru "Z"
Distric of Columbia
other, not listed, not able to classify

Answer: 5