Answer :
As per given by the question,
There are given that ,
[tex]\theta=\frac{\pi}{3}[/tex]Now,
For cartesian form;
Suppose,
[tex]\frac{y}{x}=\tan (\theta)[/tex]Then,
[tex]\begin{gathered} \frac{y}{x}=\tan (\theta) \\ y=\tan (\theta)x \end{gathered}[/tex]Now,
Put the value of theeta in above formula,
So,
[tex]\begin{gathered} y=\tan (\theta)x \\ y=\tan (\frac{\pi}{3})x \\ y=\sqrt[]{3x} \end{gathered}[/tex]Hence, the option C is correct.