Final answer:
Effective hand hygiene is the single most important activity for preventing and controlling infection in a health-care setting.
Step-by-step explanation:
The single most important activity for preventing and controlling infection in a health-care setting is effective hand hygiene. Hand washing is critical for public health and should be emphasized in a clinical setting. Health-care workers should wash their hands thoroughly between every patient contact, after removal of gloves, after contact with bodily fluids and potentially infectious fomites, and before and after assisting with invasive procedures.