Gain of an RC low pass filter having a time constant $$‘\tau’$$ and frequency $$‘\omega’$$ is:

A

$$ \sqrt{1+(\omega \tau)^2} $$

B

$$ \frac {1}{\sqrt{1+(\omega \tau)^2}} $$

C

$$ \frac {\omega \tau}{\sqrt{1+(\omega \tau)^2}} $$

D

$$ \frac {\omega \tau}{\sqrt{1-(\omega \tau)^2}} $$