Answer:
Option C is correct

Explanation:
The Proportional relationship says that:
then
the equation is of the form :
y = kx .....[1] where k is the constant of Proportionality
As per the statement:
Constant of proportionality (k) =

Substitute in [1] we get;

Therefore, an equation represents a proportional relationship that has a constant of proportionality equal to 1/5 is
