Please can someone tell me how to do this and what the answer?

Which of the following transformations will result in an image that maps onto itself? a. rotate 90 degrees counterclockwise and then reflect across the y axis b. reflect across the x-axis and then reflect across the y-axis c. rotate 90 degrees counterclockwise and then translate 4 units up d. reflect across the x-axis and then reflect again across the x-axis