In this task, you need to provide the correct option for a given problem from the provided options.
Q: Problem: the 7 th grade french and spanish classes each have 21 students in them , and there are 6 students in the 7 th grade taking both languages . if everyone in the 7 th grade is in at least one of the two language classes , how many students are taking just one of the two classes ?
Options: a ) 24 , b ) 28 , c ) 30 , d ) 32 , e ) 34
A:
c