Beth's first step is option A. Construct the perpendicular bisector of AC.
Given,
Beth is constructing the circumscribed circle for △ABC.
We have to find the first step of Beth for constructing the circumscribed circle for △ABC.
Circumcenter:
The circumcenter is the center of a triangle's circumcircle.
It can be found as the intersection of the perpendicular bisectors or We know that the circumcenter of triangle always passes through the point, where the perpendicular bisector of any two sides of that triangle passes.
Since here all the options except option A has started to draw the angle bisector
so these options are false in case to draw the circumscribed circle △ABC.
So, the first step of Beth to draw the circumscribed circle for △ABC is to Construct the perpendicular bisector of side AC.
Hence Beth's first step is option A. Construct the perpendicular bisector of AC.
For more details on circumcircle of triangle follow the link:
https://brainly.com/question/4424318