The line passes through the origin. Hence, the equation of the line is of the form:
[tex]\begin{gathered} y=kx \\ \text{ Where k is a constant} \\ \text{k is the constant of proportionality} \end{gathered}[/tex]
The point (1,5) is on the line.
Substituting the x-value and the y-value of the point (1,5) into the equation, we have
[tex]\begin{gathered} 5=k(1) \\ \text{Hence,} \\ k=5 \end{gathered}[/tex]
Thus the constant of proportionality is 5.
The correct option is C
