What must all searches and seizures adhere to under the 4th Amendment?

All searches and seizures must adhere to the standard of "reasonable" as established by the 4th Amendment to the United States Constitution. This amendment protects individuals against unreasonable searches and seizures, ensuring that law enforcement authorities must have a justified reason or probable cause to conduct a search—or to seize evidence. The term "reasonable" refers to the expectation of privacy that individuals have and the need for law enforcement to balance that against public safety concerns.

While other options like "reasonable suspicion" are relevant in specific contexts, such as stops and detentions, the overarching requirement from the 4th Amendment is that searches and seizures must be reasonable, taking into account the totality of the circumstances. Thus, this concept of reasonableness is fundamental to maintaining a balance between individual rights and public safety.