On a coordinate plane, triangle B C D has points (negative 4, 1), (negative 2, 1), (negative 4, 3). Triangle B prime C prime D prime has points (negative 1, negative 4), (negative 1, negative 2), (negative 3, negative 4). Triangle BCD is rotated counterclockwise to form triangle B’C’D’. What is the angle of rotation? 45° 90° 180° 360°