ANSWER
The constant of direct variation is [tex]k=\frac{8}{5}[/tex]
EXPLANATION
Since the equation goes through the point [tex](5,8)[/tex], it must satidfy its equation.
We therefore, substitute the point [tex](5,8)[/tex], in to the equation and solve for [tex]k[/tex].
[tex]y=kx[/tex]
This implies that;
[tex]8=5k[/tex]
[tex]\Rightarrow \frac{8}{5}=k[/tex]
Therefore the constant of direct variation is [tex]k=\frac{8}{5}[/tex]
Hence the correct answer is D.
