The vertices of triangle DEF are located at (3, 2), (6, 1), and (7, 5).
Which coordinates are the vertices of triangle D'E'F' after DEF has been reflected across the x-axis?
A. (-3, 2), (-6, 1), (-7, 5) B. (3, -2), (6, -1), (7, -5) C. (2, 3), (1, 6), (5, 7) D. (2, -3), (1, -6), (5, -7)