Use this information to answer the next two problems.

Back in 2008, the world's most accurate clock was the NIST-F1 built by the National Institute of Standards and Technology in Boulder Colorado. It is an atomic clock that is accurate to a ten-billionth of a second. Coordinated Universal Time is the official world time. The governing body that sets the Coordinated Universal Time uses an average of 400 different atomic clocks in 50 countries.

1. A statistical reason for using the average of 400 different atomic clocks instead of just using the time given by the NIST-F1 is that

Group of answer choices

a. this is likely to be a more valid measure of the true time.

b. this is likely to be a less biased measure of the true time.

c.this is likely to improve the correlation between the times of the different clocks.

d. this is likely to be a more reliable measure of the true time.

2.A couple of years ago, a team of physicists at the National Institute of Standards and Technology invented a new design that was another 10000 times more accurate than the NIST-F1 and built two of the new clocks. These two clocks can make for an even more accurate measurement of time by

a. averaging their two readings

b. using them as a gold standard to calibrate the NIST-F1

c. choosing one of the two at random and using the time from that on