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 "private business (including criminal enterprises)". Your task is to determine what category of business best describes the area of activity of this litigant which is involved in this case.

Opinion:
UNITED STATES of America v. Martin W. RUDOLPH, doing business as Seifert Trucking Co., Appellant.
No. 15495.
United States Court of Appeals Third Circuit.
Submitted May 19, 1966.
Decided June 2, 1966.
Martin W. Rudolph, pro se.
David M. Satz, Jr., U. S. Atty., Jerome D. Schwitzer, Asst. U. S. Atty., Newark, N. J., for appellee.
Before STALEY, Chief Judge, and McLAUGHLIN and SMITH, Circuit Judges.
OPINION OF THE COURT
PER CURIAM.
The appellant, Martin W. Rudolph, was tried and convicted before the district court, sitting without a jury, of transporting property in interstate commerce without having obtained a certificate of convenience and necessity as required by 49 U.S.C. § 306(a). Such conduct is criminal if knowingly and willfully committed, 49 U.S.C. § 322(a).
At the request of appellant, this appeal was submitted to the court on briefs. We have reviewed the record in the light of the alleged errors; we can perceive no error in the district court’s conclusion that appellant knowingly and willfully violated 49 U.S.C. § 306(a). See Steere Tank Lines, Inc. v. United States, 330 F.2d 719 (C.A.5, 1963). We also fail to discern any reliance by the district court on appellant’s failure to testify as a basis for his guilt.
The judgment of conviction and order denying the motion for a new trial by the district court will be affirmed.

Question: This question concerns the first listed appellant. The nature of this litigant falls into the category "private business (including criminal enterprises)". What category of business best describes the area of activity of this litigant which is involved in this case?

Choices:
agriculture
mining
construction
manufacturing
transportation
trade
financial institution
utilities
other
unclear

Answer: 4