Childhood memoirs often gain their poignancy through a sense of displacement: each lesson is accompanied by a loss of ______.

A．Saving the majority would necessarily justify the death of the minority.
B．The immune system can be trained to fight weaker versions of a disease.
C．Mandatory vaccinations are indispensable to the survival of the populace.
D．The process of vaccination remains a mystery to be further resolved.

A．Wish to claim their rights and freedom.
B．Ambition and self-fulfillment.
C．Financial incentives.
D．Desire for a social life.