Sophie's Thesis Study Is Focused on Participants' Retrospective Accounts About

Sophie's thesis study is focused on participants' retrospective accounts about happy and sad events in their lives, as well as current events identified as happy and sad. One way in which Sophie plans to control for retrospective bias in the participants' current experiences is to have these participants:

A) obtain baseline data.
B) include pretest and posttest measures.
C) keep a behavior diary.
D) stay in the study, even if they verbalize they want to drop out..