Design a brief immunological explanation for why a live attenuated vaccine often generates longer-lasting protection than an inactivated vaccine. Which combination of mechanisms best explains this difference?

• A. Live attenuated vaccines create lasting protection because they convert B cells into macrophages that then present antigen indefinitely, while inactivated vaccines destroy B cells outright preventing memory formation.
• B. Live attenuated vaccines are more effective because they bypass antigen presentation entirely and force direct antibody production by native tissues, while inactivated vaccines fail because they rely only on the complement system and do not engage adaptive immunity.
• C. Live attenuated vaccines replicate to some extent in the host, providing a broader range and duration of antigen presentation (including endogenous MHC I presentation), stronger T cell activation, and more potent germinal center reactions that produce high-affinity memory B cells and long-lived plasma cells, whereas inactivated vaccines usually provide less antigen persistence and weaker cellular responses.
• D. Live attenuated vaccines work primarily by transferring maternal immune cells which then become permanent residents, while inactivated vaccines physically block antigen-presenting cells and so cannot create memory; this is why live vaccines always produce lifelong sterilizing immunity even after a single dose.

Answer: (C)