Which instructions can be used to find the center of the circle correctly:
Step 1: Draw a line across the circle near the edge so it cuts the circumference in two places. This is called a chord.
Step 2: Draw a line perpendicular to the chord, half way along it's length.
Now you know why it's easier to pick an easy length to start with.
Make sure it goes past where the center of the circle should be. You can go straight across if that's easier.
Step 3: If you're not that confident of your measurements, then you can use as many chords as you like, until you're happy with the result.
Once you have the center marked you can use this information for other things, like drilling a hole in the middle, drawing concentric rings
Hence the correct answer is Option B