Answer:
D.function notation
Step-by-step explanation:
we know that any function can be written as
For inversely proportional
[tex]y=\frac{k}{x}[/tex]
where
k is constant of proportionality
For directly proportional
[tex]y=kx[/tex]
where
k is constant of proportionality
We can see that constant of proportionality is of functions
So,
The constant of function notation is the value that relates two variables that are directly or inversely proportional