I think it’s the last one but I’m not sure
The surface area of a cylinder with circular bases of radius <em>r</em> and height <em>h</em> is equal to the sum of the areas of the two circular faces and the area of the rectangular lateral surface:
<em>A</em> = 2π<em>r</em>² + 2π<em>rh</em>
If you know the height <em>h</em>, then you can solve the quadratic equation for <em>r</em>.