A vaccination programme is successful when it creates a level of immunity in which most individuals in a population are protected. Several factors can influence how successful a vaccination programme is. Which row correctly identifies the factors that can influence how successful a vaccination programme is?
- Afrequent mutation ✓, vaccination from eight weeks old ✓, pathogen invades T-cells \times, boosters needed ✓
- Bfrequent mutation ✓, vaccination from eight weeks old \times, pathogen invades T-cells ✓, boosters needed ✓
- Cfrequent mutation \times, vaccination from eight weeks old ✓, pathogen invades T-cells ✓, boosters needed \times
- Dfrequent mutation ✓, vaccination from eight weeks old \times, pathogen invades T-cells ✓, boosters needed \times