Which Should the Nurse Implement as the Most Important Measure

Which should the nurse implement as the most important measure in preventing transmission of harmful pathogens to patients with depressed bone marrow function?

A) Strict and frequent handwashing by all people having contact with the patient
B) Placement of patients in private rooms with high-efficiency particulate air (HEPA) filtration
C) Administration of combinations of prophylactic antibiotics
D) Creation of a "sterile" environment for the patient with the use of laminar airflow rooms