Final answer:
The holding in U.S. v. Salerno is that the dangerousness of a defendant can be considered an exception to pretrial release, allowing detention without bail when the individual poses a significant threat to public safety.
Step-by-step explanation:
The rule/holding in U.S. v. Salerno is C) The dangerousness exception to pretrial release.
The Supreme Court in United States v. Salerno, 481 U.S. 739 (1987), upheld the Bail Reform Act of 1984, which allows the federal courts to detain an arrestee pretrial if they are deemed dangerous to the community. The case concluded that the Act's provisions were a lawful regulation of bail, which did not contravene the Constitution. The Court found that when Congress determines that arrestees are a danger to others or the community, their pretrial detention can be justified.
This decision made it clear that the government could deny bail for a limited period of pretrial detention, based on a compelling interest in public safety, without violating the due process rights of the detainee.