I believe it is the final sentence: I left for college when I was 18 (that was also the age at which I was married). This is because the parentheses also give information about another incident that took place at the time - his/her marriage.
The answer is: inaction.
Quietism was a movement which started in Spain, France and Italy in 1600s. It believed in the passivity of spirituality and in a contemplative life. It also assumed that perfection could be achieved by the abolition of will, so God would approach someone when its soul is in a quiet state, without any reasoning or executing any actions. As a result, man would accept whatever God grants him.
Answer:
B. the point when the tension in the story is at its highest