How many justices must agree to grant a writ of certiorari?

To grant a writ of certiorari, typically four justices of the Supreme Court must agree. This is often referred to as the "Rule of Four." The purpose of this rule is to ensure that a significant minority of the justices believes that the case has sufficient importance or merits to be heard by the Court. This practice helps manage the Court's docket, allowing it to focus on pivotal cases that may have broader implications for law or society.

The other options suggest differing numbers of justices, which do not align with the established Rule of Four. Five justices would constitute a majority, but a majority is not required for certiorari; instead, this rule allows for just a minority to determine if a case has merits worth hearing. Meanwhile, three or seven justices would not fulfill the Court's procedural requirements for certiorari.