C-01-Q109mediumsingle_mcqThe vibration frequency of Cs-133 used to define the second is—a9,192,631,7709{,}192{,}631{,}7709,192,631,770 Hzb6.62607015×10−346.62607015 \times 10^{-34}6.62607015×10−34 Hzc1.602176634×10−191.602176634 \times 10^{-19}1.602176634×10−19 Hzd6.02214076×10236.02214076 \times 10^{23}6.02214076×1023 Hz