[问答题]
The graph shows the typical imxb; unr 8d/--knwdwp2mune response to two dosc 1n(ak +5fehtg*(e.qwgupt2 es of a vaccine.
1.State which type of molecule stimulates antibody production.
2.Distinguish between the primary and secondary responses.
3.Explain how vaccination leads to long-term immunity.
