A nurse is initiating a protective environment for a client who has had an allogeneic stem cell transplant. Which of the following precautions should the nurse plan for this client?

The correct answer is A: Make sure the client's room has at least six air exchanges per hour. This is essential for a protective environment post-allogeneic stem cell transplant to reduce the risk of infection. Increasing air exchanges helps remove airborne pathogens and maintain a clean environment. Option B is incorrect as wearing a mask outside the room is not a part of a protective environment. Option C is incorrect as negative-pressure airflow is typically used for clients with airborne infections, not for stem cell transplant clients. Option D is incorrect as N95 respirators are not routinely required for providing direct care in a protective environment setting.