Q: The fundamental unit of time, the second, is based on what type of clock?


Read this paragraph and choose the correct option from the provided answers:

Figure 1.18 An atomic clock such as this one uses the vibrations of cesium atoms to keep time to a precision of better than a microsecond per year. The fundamental unit of time, the second, is based on such clocks. This image is looking down from the top of an atomic fountain nearly 30 feet tall! (credit: Steve Jurvetson/Flickr).

 Choices:

- quantum clock

- eternal clock

- gravity clock

- atomic clock


A:
atomic clock