The diagonal of the square will be the diameter of the circle.
The radius is 1, so the diameter is 2.
Let x= one side of Square, So the area will be x2
Using the Pythagorean theorem (and knowing that all sides of a square are congruent) we get:
x2+ x2= 4
Area of Square(x2) = 2
Hence,Option(B)2 is the correct choice.