Angle MNO is formed by segments MN and NO on the coordinate grid: A coordinate plane is shown. Angle MNO has vertices at negative 4 comma 4 and negative 2 comma 2 and negative 4 comma 1 and measures 71.57 degrees.
Angle MNO is rotated 180 degrees counterclockwise about the origin to form angle M′N′O′. Which statement shows the measure of angle M′N′O′? (4 points)

a
m∠M′N′O′ = 90 degrees

b
m∠M′N′O′ = 180 degrees

c
m∠M′N′O′ = 2 × m∠MNO

d
m∠M′N′O′ = m∠MNO