Final answer:
A. The courtiers' decision to allow people to leave the abbey but never to re-enter shows that they value collective security over individual freedom.
Step-by-step explanation:
The description of the courtiers resolving 'to leave means neither of ingress or egress' in paragraph 2 reveals that the courtiers value collective security over individual freedom. By not allowing anyone to leave or enter the abbey during the time of the plague, they are prioritizing the safety and protection of the community over personal desires. This decision suggests that they believe isolating themselves from the outside world is necessary to prevent the spread of the disease.