Step-by-step explanation:
Most accurate means the value which is more close to the accepted value which is 2.99792458 x 10⁸ m/s.
More precise means the value which is very close to each other and they also may not be close to the accepted value. It can be stated that the values which are having less amount of deviations.
Hence, Cg is most accurate and Cc is most precise.