Under the United States Constitution, which of the following matters concerning the Supreme Court is not directly specified in the text and is therefore left to Congress to decide?

Introduction / Context:
Article three of the United States Constitution establishes the judicial branch. It lays down the existence of a Supreme Court and allows Congress to create lower courts. However, not every detail about the Supreme Court is written into the Constitution. This question asks which important aspect of the Court is not fixed by the text and is instead left for Congress to determine by ordinary legislation.

Given Data / Assumptions:

• The Constitution clearly creates a Supreme Court.
• It describes judicial tenure and some protections for judges.
• It gives Congress power to establish inferior courts.
• The options refer to number of justices, existence of the Court, tenure, salaries, and power to establish lower courts.

Concept / Approach:
To answer, we must separate what is explicitly written from what is left open. The Constitution states that there shall be one Supreme Court, that judges shall hold office during good behaviour, that they shall receive a compensation which shall not be diminished while they are in office, and that Congress may from time to time ordain and establish inferior courts. The text does not state how many justices the Supreme Court must have. Historically, Congress has changed the number by statute, which confirms that this detail is left to Congress.

Step-by-Step Solution:
Step 1: Recall the main clauses of Article three regarding the Supreme Court. Step 2: Identify which options track those clauses exactly, such as existence, tenure, salary protection, and power to create lower courts. Step 3: Notice that the number of justices is not specified in the text; the Constitution does not say nine or any other figure. Step 4: Conclude that the exact number of justices is the issue left open for Congress and therefore is the correct answer.

Verification / Alternative check:
Historically, Congress has passed several Judiciary Acts that have changed the size of the Supreme Court, demonstrating that the number of justices is a matter of legislation. If the Constitution had fixed the number, Congress could not change it by ordinary law. This practical history verifies that the number of justices is not a constitutional constant but a statutory decision.

Why Other Options Are Wrong:
That there shall be a Supreme Court: This is explicitly provided in Article three. That federal judges hold office during good behaviour: This phrase appears in the judicial tenure clause. That Congress may establish inferior federal courts: This is also stated in Article three, giving Congress power to ordain and establish lower courts. That judges shall receive a salary that cannot be reduced while in office: Salary protection is clearly written to safeguard judicial independence. Because these matters are directly specified, they are not the unanswered question.

Common Pitfalls:
Many learners know there are nine justices and incorrectly assume this number must be written into the Constitution. In reality, nine is simply the current statutory number. Another pitfall is failing to distinguish between constitutional text and practices that have developed over time, such as the rule of four or lifetime tenure interpreted through good behaviour. Only the text itself determines what is fixed and what is flexible.

Final Answer:
The exact number of justices on the Supreme Court