A square is inscribed in a circle x² + y² + 2x + 2y + 1 = 0 and its sides are parallel to coordinate axes. Which one of the following is a vertex of the square?

Circle: (x+1)² + (y+1)² = 1, centre (-1,-1), radius 1. Inscribed square with sides parallel to axes has half-diagonal = radius = 1, so half-side = 1/√2. Vertices: (-1 ± 1/√2, -1 ± 1/√2). Option (c) has (-1 + 1/√2, -1 - 1/√2) which matches. So answer is (c)... but checking: option (c) is exactly a vertex. So correct index is 2.