We have, since the beginning, identified the points A, B and C in the figure.
As you can see, the third option is not possible as that point is the result of the whole construction process.
Since the last option seems to be incorrect, and it is equivalent to the second option, we can deduced that the first step is the first option:
Place the compass on point A and draw arc CB
However, it is important to notice that you can start by doing the first, second or fourth option, provided that the point B and C are given.