Correct Answer: B — Primary prevention

Levels of Prevention (Leavell & Clark):

Level	Goal	Examples
Primordial	Prevent risk factors from emerging	Health policies, societal change
Primary	Prevent disease before it occurs	Vaccination, health education, sanitation
Secondary	Early detection and prompt treatment	Screening tests, early diagnosis (e.g., mammography, TB skin test)
Tertiary	Reduce disability; rehabilitation	Physiotherapy, chronic disease management, support groups

Hepatitis B vaccination prevents disease before exposure occurs — this is primary prevention (health protection). Note: Secondary prevention would be testing nurses for hepatitis B exposure after a needlestick injury.