A circular graphic is divided into four quadrants. Quadrants I, II, and III each contain a black sector of 60 degrees adjacent to the positive horizontal axis in that quadrant. To maintain four-fold rotational symmetry, what must Quadrant IV contain?
Options:
(A) A black sector of 60 degrees adjacent to the positive horizontal axis in Quadrant IV
(B) A completely shaded quadrant
(C) An unshaded empty quadrant
(D) A 30-degree sector adjacent to the vertical axis
Answer Key:
A
Step-by-Step Solution & Explanation
Under four-fold rotational symmetry (C_4), each quadrant must be an identical 90-degree rotated copy of the others, preserving the relative position of the 60-degree sector.