Which element is NOT typically associated with atomic clocks used in GPS?

Atomic clocks are highly precise timekeeping devices that are essential for GPS technology. They operate based on the vibrations of atoms, which serve as the reference for measuring time. Among the elements commonly used in atomic clocks, cesium and rubidium are the most prevalent, with cesium clocks setting the standard for the definition of the second. Hydrogen maser clocks are also utilized in various high-precision timing applications.

Oxygen, however, is not typically associated with atomic clocks. While it plays roles in other scientific contexts—such as spectroscopy and various chemical reactions—it's not a standard element used in the design or operation of atomic clocks. Therefore, the correct answer highlights that oxygen does not have a role in the functioning of GPS atomic clocks like the other elements listed. This distinction is important for understanding the technology behind global positioning systems.