Which amendment requires law enforcement to obtain a warrant before conducting a search?

The Fourth Amendment is the correct choice because it explicitly protects individuals from unreasonable searches and seizures by law enforcement. It establishes the requirement that law enforcement must obtain a warrant, which is a legal document authorized by a judge or magistrate, based on probable cause. This constitutional safeguard ensures that citizens' privacy rights are respected and that searches and seizures are conducted lawfully.

The other amendments listed do not pertain to search and seizure. The Third Amendment deals with the quartering of soldiers in private homes, the Fifth Amendment addresses rights related to legal proceedings, including protection against self-incrimination and double jeopardy, and the Sixth Amendment guarantees rights related to criminal prosecutions, such as the right to a fair trial and legal counsel. Thus, the Fourth Amendment is specifically designed to protect against arbitrary intrusions into personal privacy by requiring legal scrutiny before such actions can be taken.