The SI standard of time is based on_____________?

A. a precision pendulum clock

B. none of these

C. the frequency of light emitted by Kr86

D. the daily rotation of the earth

E. the yearly revolution of the earth about the sun

Found an error? Read our corrections policy and submit a sourced correction below. You can also share a useful explanation in your own words.

Discuss the answer or suggest a sourced correction
Thank you for contributing.
Your comment was submitted and will appear after editorial review.

Your email is used only for moderation and is never displayed. Spam, copied material and fabricated endorsements are rejected.