The musical frequency of notes is decreasing between beat numbers and

The complete question in the attached figure

we have that
between beats 2 and 3----------> (392-261.6)=130.4-------> increases
between beats 3 and 4----------> (392-392)=0-----> it stays with the same value
between beats 4 and 5----------> (444-392)=52--------> increases
between beats 5 and 6----------> (444-444)=0-----> it stays with the same value
between beats 6 and 7----------> (392-444)=-52-------> decreases

the answer is
between beats 6 and 7----------> (392-444)=-52-------> decreases

The following relation is not a function