Jenny and her friends picked out some paper chits from a glass bowl. Each of these chits had some numbers on them.
Jenny's chit had the number 16.
Kaira's chit had a number that was the square root of the number on Jenny's chit.
Also, Sia's chit had a number that was the square root of the number on Kaira's chit.
Which of the following numbers appeared on Sia's chit?