Answer: Third option is correct.
Step-by-step explanation:
Since we have given that
[tex]y=\log 5x[/tex]
As we know that logarithm is the opposite of exponential function:
So, it becomes,
[tex]y=\log 5x\\\\e^y=5x\\\\x=\frac{e^y}{5}[/tex]
On the other hand,
y=5x, y=6x are the linear funtions.
And [tex]y=x^2[/tex] is the quadratic function.
Hence, Third option is correct.