Be Clean, Be GreenDear Guests,Each year, many of the major waterways in the world get polluted by vast amounts of detergents used to wash bed linen and towels in hotels.In an effort to help preserve the environment, we’d like to ask all of our guests to please leave the towels that you intend to re-use on the towel rack and place those towels you want exchanged in the bathtub.May we also ask that you leave this card on the bed if you do not require your bed linens changed ？We’d like to thank you for your cooperation in helping to improve our environment.The Management What is being asked of those who do not want their bed sheets changed to do ？（）

A. Call the management staff
B. Talk to the hotel maid
C. Leave a do-not-disturb sign on the door
D. Place the card on the bed