What follows is an opinion from the Supreme Court of the United States. Your task is to determine the bases on which the Supreme Court rested its decision with regard to the legal provision that the Court considered in the case. Consider "judicial review (national level)" if the majority determined the constitutionality of some action taken by some unit or official of the federal government, including an interstate compact. Consider "judicial review (state level)" if the majority determined the constitutionality of some action taken by some unit or official of a state or local government. Consider "statutory construction" for cases where the majority interpret a federal statute, treaty, or court rule; if the Court interprets a federal statute governing the powers or jurisdiction of a federal court; if the Court construes a state law as incompatible with a federal law; or if an administrative official interprets a federal statute. Do not consider "statutory construction" where an administrative agency or official acts "pursuant to" a statute, unless the Court interprets the statute to determine if administrative action is proper. Consider "interpretation of administrative regulation or rule, or executive order" if the majority treats federal administrative action in arriving at its decision.Consider "diversity jurisdiction" if the majority said in approximately so many words that under its diversity jurisdiction it is interpreting state law. Consider "federal common law" if the majority indicate that it used a judge-made "doctrine" or "rule; if the Court without more merely specifies the disposition the Court has made of the case and cites one or more of its own previously decided cases unless the citation is qualified by the word "see."; if the case concerns admiralty or maritime law, or some other aspect of the law of nations other than a treaty; if the case concerns the retroactive application of a constitutional provision or a previous decision of the Court; if the case concerns an exclusionary rule, the harmless error rule (though not the statute), the abstention doctrine, comity, res judicata, or collateral estoppel; or if the case concerns a "rule" or "doctrine" that is not specified as related to or connected with a constitutional or statutory provision. Consider "Supreme Court supervision of lower federal or state courts or original jurisdiction" otherwise (i.e., the residual code); for issues pertaining to non-statutorily based Judicial Power topics; for cases arising under the Court's original jurisdiction; in cases in which the Court denied or dismissed the petition for review or where the decision of a lower court is affirmed by a tie vote; or in workers' compensation litigation involving statutory interpretation and, in addition, a discussion of jury determination and/or the sufficiency of the evidence.

Opinion:
ARKANSAS v. TENNESSEE
No. 33,
Orig.
Argued January 19, 1970
Decided February 25, 1970
Don Langston, Assistant Attorney General of Arkansas, argued the cause for plaintiff on exceptions to the Report of the Special Master. With him on the brief was Joe E. Purcell, Attorney General.
Heard H. Sutton argued the cause for defendant in support of the Report of the Special Master. With him on the brief were David Pack, Attorney General of Tennessee, C. Hayes Cooney, Assistant Attorney General, Harry W. Laughlin, James L. Oarthright, Jr., and J. Martin Regan.
Per Curiam.
This original action was commenced on October 13, 1967, by the State of Arkansas to settle a boundary dispute with the State of Tennessee. The disputed area extends six miles laterally along the west (Arkansas side) bank of the Mississippi River and encompasses some five thousand acres. This Court's jurisdiction arises under Art. Ill, § 2, of the Constitution of the United States. On January 15, 1968, we appointed, 389 U. S. 1026, Hon. Gunnar H. Nordbye, Senior United States Judge of the District of Minnesota, as Special Master to determine the state line in the disputed area known as Cow Island Bend in the Mississippi River located between Crittenden County, Arkansas, and Shelby County, Tennessee. After conducting an evi-dentiary hearing and viewing the area, the Master filed his Report with this Court recommending that all of the disputed area be declared part of the State of Tennessee. We affirm the Master’s Report.
The parties agree that the state line is the thalweg, that is, the steamboat channel of the Mississippi River as it flows west and southward between these States. The Master heard evidence and was presented exhibits and maps which showed that the migration of the Mississippi River northward and west continued until about 1912. At this time an avulsion occurred leaving Tennessee lands on the west or Arkansas side of the new or avulsive river channel. The Master found that thereafter, because of the avulsion, the water in the thalweg became stagnant and erosion and accretion no longer occurred. At this time the boundary between Arkansas and Tennessee became fixed in the middle of the old abandoned channel.
This is a classic example of the situation referred to in an earlier case between these States, Arkansas v. Tennessee, 246 U. S. 158, 173, where we said,
"It is settled beyond the possibility of dispute that where running streams are the boundaries between States, the same rule applies as between private proprietors, namely, that when the bed and channel are changed by the natural and gradual processes known as erosion and accretion, the boundary follows the varying course of the stream; while if the stream from any cause, natural or artificial, suddenly leaves its old bed and forms a new one, by the process known as an avulsion, the resulting change of channel works no change of boundary, which remains in the middle of the old channel, although no water may be flowing in it, and irrespective of subsequent changes in the new channel.”
And, again, id., at 175,
“An avulsion has this effect, whether it results in the drying up of the old channel or not. So long as that channel remains a running stream, the boundary marked by it is still subject to be changed by erosion and accretion; but when the water becomes stagnant, the effect of these processes is at an end; the boundary then becomes fixed in the middle of the channel as we have defined it, and the gradual filling up of the bed that ensues is not to be treated as an accretion to the shores but as an ultimate effect of the avulsion.”
The exceptions of the State of Arkansas are overruled and the Report of the Special Master is adopted.
It is ordered that the Hon. Gunnar H. Nordbye be, and he is hereby, appointed as Commissioner in this case with power to engage and supervise a competent surveyor, or surveyors, to survey the boundary line as recommended in the Master’s Report. The boundary line determined by such survey shall be submitted to the Court by the Commissioner and, if approved, shall be the boundary line between the two States.
The costs of this proceeding shall be divided equally between the parties.

Question: What is the basis of the Supreme Court's decision?

Choices:
judicial review (national level)
judicial review (state level)
Supreme Court supervision of lower federal or state courts or original jurisdiction
statutory construction
interpretation of administrative regulation or rule, or executive order
diversity jurisdiction
federal common law

Answer: 2