Which Is the BEST Example of Retrospective Analysis

Which is the BEST example of retrospective analysis?

A) Researchers ask college students to write suicide notes to study what they think is the motivation for suicide.
B) Therapists who had patients who committed suicide are interviewed to gain information on suicide.
C) Adolescents at high risk for suicide are treated through a suicide prevention center.
D) Those who have made suicide attempts are part of a suicide education program.