Https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-data-statistics/cc-6th/v/calculating-interquartile-range-iqr
This is a link that I gave to my little sister that helped her understand what interquartile range is. It has an example as well! I hope this helps!
Answer is 14.14
Reason
Using Pythagorean theory
a^2 + b^2 = c^2
The two legs are a and b, the longest diagonal opposite the right angle is c
10^2 + 10^2 = c^2
200 = c^2
Take square root of both sides
14.14 = c
The answer is A. it has two complex solutions