What does the 4th Amendment protect individuals against?

The 4th Amendment to the United States Constitution is designed to protect individuals from unreasonable searches and seizures by the government. This protection primarily emphasizes the necessity of a warrant, which requires probable cause and is intended to ensure that searches are justified and that individual privacy is respected.

Selecting physical intrusion without a warrant as the correct answer aligns with the core principle of the 4th Amendment. Without a warrant, law enforcement cannot lawfully enter an individual’s home or personal property to conduct a search, thereby protecting citizens from arbitrary government actions and maintaining a level of personal privacy.

Other options describe situations that do not typically fall under the protections granted by the 4th Amendment. For instance, all forms of surveillance could include lawful monitoring that doesn't constitute a search or seizure under the amendment. Searches conducted by civilians may not involve government action and thus are not governed by the 4th Amendment. Similarly, gathering evidence in public places is generally permissible because individuals do not have a reasonable expectation of privacy in those areas. Each of these highlights aspects of the amendment’s application while affirming the critical focus on unwarranted government intrusion as central to its protections.