1954Every Day ScienceMedium
The SI standard of time is based on_____________?
Athe frequency of light emitted by Kr86
Ba precision pendulum clock
Cthe daily rotation of the earth
Dnone of these
Ethe yearly revolution of the earth about the sun
Correct answer
D. none of these
Explanation
none of these is the correct answer. Review the question and compare it with the other choices to remember this fact for future exams.