Which Mandatory Practice Is the Most Effective and Significant Nursing

Which mandatory practice is the most effective and significant nursing practice to prevent the spread of infection?

A) Strict and frequent hand washing 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