How Do You Calculate the Interquartile Range for a Data

How do you calculate the interquartile range for a data set?

A) Take the highest value minus the lowest value and divide it by four.
B) Subtract the value of the lower quartile from the upper quartile.
C) Subtract the value of the upper quartile from the lower quartile.
D) Divide the data set into four equal parts and find the range between each of the resulting quarters.