Answer:
Mark the points of intersection between circle A and line AB.
Explanation:
The attached shows an inscribed square created using technology. We started with point A and B, drew the circle with radius AB, and drew the line AB. Then we marked point C at the intersection of circle A and line AB.
We had a perpendicular to AB drawn through A, and marked its intersection with circle A as points D and E. Finally, we drew inscribed square BDCE.
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Other answer choices may somehow be involved. We'd need to see the construction to be sure. The one shown above seemed most likely.