Correct option is C
Atomic clocks are the most precise timekeeping devices, capable of measuring
extremely small time intervals with
accuracy up to nanoseconds (10⁻⁹ s) or even better. They operate based on the
vibrations of atoms (usually cesium or rubidium), which oscillate at highly stable frequencies.
For example:
·
Cesium atomic clocks use the
microwave radiation emitted during the transition of cesium-133 atoms.
· The
official definition of a second is based on
9,192,631,770 cycles of radiation from a cesium atom.
