Final answer:
Sarah 'volunteers' every weekend at the library to help students, which signifies her choice to offer service without payment. This mirrors the activities of the retired woman who stays active in the community, relating to the theory of continuous involvement improving post-retirement life.
Step-by-step explanation:
The correct answer is 'b) volunteers'. So, the full sentence should read: Sarah volunteers every weekend at the library to help students in her community. This means that Sarah offers her time and service without being paid because she wants to support the students. The use of 'volunteers' is consistent with the other activities mentioned for the older woman, who engages in various community and social activities after retiring. These activities illustrate an active engagement with the community and an enriching lifestyle post retirement, which relates to the theory of continuous involvement and social interaction being important for well-being after major life changes like retirement.