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 "natural person (excludes persons named in their official capacity or who appear because of a role in a private organization)". Your task is to determine the citizenship of this litigant as indicated in the opinion.

Opinion:
PETERSON v. MARZALL.
No. 11131.
United States Court of Appeals District of Columbia Circuit.
Argued Feb. 21, 1952.
Decided March 13, 1952.
Joseph N. Nielsen, Washington, D. C., for appellant.
H. S. Miller, United States Patent Office, Washington, D. C., with whom E. L. Reynolds, Solicitor, United States Patent Office, Washington, D. C., was on the brief, for appellee.
Before EDGERTON, PROCTOR, and BAZELON, Circuit Judges.
PER CURIAM.
This is a suit under 35 U.S.C.A. § 63, R.S. § 4915, for a patent on an electrically insulating layer structure such as a floor rug. We see no reason to disturb the finding of the Patent Office and the District Court that the claims fail to show invention over the patents cited by appellee.
Affirmed.

Question: This question concerns the first listed appellant. The nature of this litigant falls into the category "natural person (excludes persons named in their official capacity or who appear because of a role in a private organization)". What is the citizenship of this litigant as indicated in the opinion?

Choices:
not ascertained
US citizen
alien

Answer: 0