Angle ABC is formed by segments AB and BC on the following coordinate grid: A coordinate grid is shown from positive 6 to negative 6 on the x axis and from positive 6 to negative 6 on the y axis. A line segment AB is shown with A as ordered pair 1, negative 1 and B as ordered pair 5, negative 4. Another line segment BC is shown with C as ordered pair 1, negative 4. Angle ABC is rotated 90 degrees counterclockwise about the origin to form angle A′B′C′. Which statement shows the measure of angle A′B′C′? m∠ A′B′C′ = 90 degrees m∠ A′B′C′ = m∠ABC m∠ A′B′C′ = 180 degrees m∠ A′B′C′ = 2 ⋅ m∠ABC