Which of the following sequence of transformations is used to obtain figure A′B′C′D′ from ABCD? (1 point)

a
Counterclockwise rotation by 180 degrees about the origin followed by translation up by 4 units

b
Reflection about the x-axis followed by translation up by 4 units

c
Reflection about the y-axis followed by translation down by 4 units

d
Counterclockwise rotation by 180 degrees about the origin followed by translation down by 4 units