A sample was taken of the salaries of 20 employees from a large company. The following are the salaries (in thousands of dollars) for this year (the data are ordered): 28, 31, 34, 35, 37, 41, 42, 42, 42, 47, 49, 51, 52, 52, 60, 61, 67, 72, 75, 77. Suppose each employee in the company receives a $3000 raise for next year (each employees salary is increased by $3000). The interquartile range of the salaries will

A) increase by $3000. B) be multiplied by $3000. C) be unchanged.