Let us first try to construct.
We shall draw a line using a straight edge.
Now we measure a small length on compass.
Place the compass at the initial point and cut an arc on the line.
Then we place the compass on the first arc and draw the second arc.
We repeat this process for the number of standard units we wish to make the ruler.
Hence we need a straight edge & a compass to make a fair ruler.
Option C) is the right answer.
