Answer:
D. 5
Step-by-step explanation:
When an equation is written in the form:
[tex]y=kx[/tex], the constant of proportionality is [tex]k[/tex].
The equation given to us is [tex]y=5x[/tex]
When we compare with [tex]y=kx[/tex], we have:
[tex]kx=5x[/tex]
This implies that:
[tex]k=5[/tex]
Hence the constant of proportionality is 5.
