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'? a) m∠ a'b'c' = 90 degrees b) m∠ a'b'c' = m∠abc c) m∠ a'b'c' = 180 degrees d) m∠ a'b'c' = 2 ⋅ m∠abc