This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to find the center of a circle
Draw a circle.
Use a compass, or trace any circular object. The size of the circle does not matter.

OPTIONS:
(1). Remove a block of wood of the same height as the circle. If the circle is too large to draw straight side up, use a box cutter to remove a block of wood.;
(2). Before you begin drawing your circle, have it centered so that it appears smaller than it actually is. Place the compass needle at the center of the circle.;
(3). That is, you can trace the circle using one " line " or, if you're left-handed, use two " lines " to trace and freehand your circle. To obtain the center of a circle, draw a circle with sides of 1 ".;
(4). If you're finding the center of an existing circle, then you don't need to draw a new circle. A geometry compass is a tool specifically designed to draw and measure circles.;
The answer is:
(4).