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.
In some cases there is some confusion over who should be listed as the appellant and who as the respondent. This confusion is primarily the result of the presence of multiple docket numbers consolidated into a single appeal that is disposed of by a single opinion. Most frequently, this occurs when there are cross appeals and/or when one litigant sued (or was sued by) multiple litigants that were originally filed in district court as separate actions. The coding rule followed in such cases should be to go strictly by the designation provided in the title of the case. The first person listed in the title as the appellant should be coded as the appellant even if they subsequently appeared in a second docket number as the respondent and regardless of who was characterized as the appellant in the opinion.
To clarify the coding conventions, consider the following hypothetical case in which the US Justice Department sues a labor union to strike down a racially discriminatory seniority system and the corporation (siding with the position of its union) simultaneously sues the government to get an injunction to block enforcement of the relevant civil rights law. From a district court decision that consolidated the two suits and declared the seniority system illegal but refused to impose financial penalties on the union, the corporation appeals and the government and union file cross appeals from the decision in the suit brought by the government. Assume the case was listed in the Federal Reporter as follows:
United States of America,
Plaintiff, Appellant
v
International Brotherhood of Widget Workers,AFL-CIO
Defendant, Appellee.
International Brotherhood of Widget Workers,AFL-CIO
Defendants, Cross-appellants
v
United States of America.
Widgets, Inc. & Susan Kuersten Sheehan, President & Chairman
of the Board
Plaintiff, Appellants,
v
United States of America,
Defendant, Appellee.
This case should be coded as follows:Appellant = United States, Respondents = International Brotherhood of Widget Workers Widgets, Inc., Total number of appellants = 1, Number of appellants that fall into the category "the federal government, its agencies, and officials" = 1, Total number of respondents = 3, Number of respondents that fall into the category "private business and its executives" = 2, Number of respondents that fall into the category "groups and associations" = 1.
Note that if an individual is listed by name, but their appearance in the case is as a government official, then they should be counted as a government rather than as a private person. For example, in the case "Billy Jones & Alfredo Ruiz v Joe Smith" where Smith is a state prisoner who brought a civil rights suit against two of the wardens in the prison (Jones & Ruiz), the following values should be coded: number of appellants that fall into the category "natural persons" =0 and number that fall into the category "state governments, their agencies, and officials" =2. A similar logic should be applied to businesses and associations. Officers of a company or association whose role in the case is as a representative of their company or association should be coded as being a business or association rather than as a natural person. However, employees of a business or a government who are suing their employer should be coded as natural persons. Likewise, employees who are charged with criminal conduct for action that was contrary to the company policies should be considered natural persons.
If the title of a case listed a corporation by name and then listed the names of two individuals that the opinion indicated were top officers of the same corporation as the appellants, then the number of appellants should be coded as three and all three were coded as a business (with the identical detailed code). Similar logic should be applied when government officials or officers of an association were listed by name.
Your specific task is to determine the total number of appellants in the case that fall into the category "natural persons". If the total number cannot be determined (e.g., if the appellant is listed as "Smith, et. al." and the opinion does not specify who is included in the "et.al."), then answer 99.

Opinion:
Myrna R. LOGSDON, mother and Administratrix of the Estate of her son Mark F. Logsdon, Deceased, Individually and as wife of Hugh E. Logsdon, Appellant, v. Joel P. BAKER et al.
No. 74-1014.
United States Court of Appeals, District of Columbia Circuit.
Argued Feb. 19, 1975.
Decided Aug. 7, 1975.
Thomas B. Lawrence, Washington, D. C., for appellant.
Anthony E. Grimaldi, Washington, D. C., for appellees.
Before BASTIAN, Senior Circuit Judge, and LEVENTHAL and ROBINSON, Circuit Judges.
Senior Circuit Judge Bastían participated in the consideration of this case but died before the judgment or memorandum was prepared.
PER CURIAM:
Mark Logsdon was killed when his motorcycle collided with a truck owned by the defendants. Plaintiff did not put the truck driver on the stand during the trial, and there were no other eyewitnesses to the accident. Believing that the evidence was insufficient to allow an expert to formulate an opinion as to the causes of the mishap, the district judge rejected plaintiff’s proffer of expert testimony, and directed a verdict for defendants.
On review, we must consider the evidence in the strongest light favoring the plaintiff just as the district court was called to do originally. See Continental Ore Co. v. Union Carbide Corp., 370 U.S. 690, 696, 82 S.Ct. 1404, 8 L.Ed.2d 777 (1962); Simmonds v. Capital Transit Co., 79 U.S.App.D.C. 371, 147 F.2d 570 (1945); 5A J. Moore, Federal Practice ¶ 50.02[1] at 2325-2329 (1974).
Reviewing the evidence, it appears that there was testimony establishing where the cycle and the body of its rider came to rest. Both the postman who arrived at the scene shortly after the accident and one of the residents of the neighborhood testified in some detail as to the location of each of the vehicles.
Plaintiff’s expert evaluated these facts and sought to draw conclusions as to the speed of the vehicles and the ability of defendant’s truck to accelerate to the suggested speed after stopping at the sign governing the controlled street, Tennyson.
There is some indication that the expert also relied on “brake marks” purportedly evident in photographs taken at the scene. Neither the district judge nor we can discern the marks in the photos. Even if they had been present, only a rather attenuated assumption could link the “brake marks” with this particular truck. If the expert relied on the “brake marks” to formulate his conclusion, we would agree that the opinion produced would be too speculative to go to the jury. But from the record, we cannot discern whether it was necessary for the expert to rely on the “brake marks” to formulate his opinion.
An expert can give his opinion on the basis of hypothetical facts, but those facts must be established by independent evidence properly introduced. If this expert could have reasonably formulated an opinion regarding causation without relying on either the existence or absence of “brake marks” then the issue should have been submitted to the jury, and a new trial should be ordered. If the district judge concludes, giving all appropriate consideration to plaintiff’s right to go to the jury if he made out a prima facie case, that the evidence was insufficient to lay a foundation for the expert’s opinion the verdict can be reinstated. Without proof of causation there can be no liability. See MacMaugh v. Baldwin, 99 U.S.App.D.C. 247, 239 F.2d 67 (1956); Reece v. Capital Transit Co., 97 U.S.App.D.C. 274, 230 F.2d 824 (1956).
The judgment of the district court is vacated, and the case remanded for further proceedings to clarify the basis of the expert’s opinion.
So ordered.
366 F.Supp. 332 (D.C.1973).

Question: What is the total number of appellants in the case that fall into the category "natural persons"? Answer with a number.

Choices:

Answer: 2