$\"\"$

The polar equation is $\"\"$ .

Transform the equation to rectanglular coordinates.

$\"\"$ .

Multiply on each side by $\"\"$ .

$\"\"$ .

Apply formula: $\"r$ and $\"\"$ .

$\"\"$

The equation represents standard equation of a circle with center at $\"\"$ in rectangular coordinates and the radius $\"\"$ .

Thus, Option $\"\"$ is correct choice.

$\"\"$

Option $\"\"$ is correct choice.