[amp_mcq option1=”100 n” option2=”50 jt” option3=”25 JT” option4=”5 n” correct=”option4″]
The correct answer is $\boxed{\text{C}}$, 25 $\pi$ rad/s.
The angular frequency is the number of radians that a sine wave goes through in one second. It is denoted by $\omega$ and is given by the formula:
$$\omega = 2\pi f$$
where $f$ is the frequency in Hz.
In this case, the frequency is 50 Hz, so the angular frequency is:
$$\omega = 2\pi (50 \text{ Hz}) = 25\pi \text{ rad/s}$$