Hi everyone! While working through Question 1, I found it helpful to remember thatcumulative incidencerefers to new cases over some time (a), whileprevalence measures existing cases at a point in time (b, d). For example, part (a) asks about freshman girls who become pregnant over their high school yearsthis is a cumulative incidence because it counts new pregnancies over time. In contrast, (b) refers to senior boys who are fathers at the time of graduation, which is point prevalence. Does anyone else find (e) the lifetime risk of breast cancer tricky? It is also a form of cumulative incidence, but over a lifetime. I would love to hear how you differentiated between these or if you use any mnemonics!