Read each scenario below and determine whether a case study, naturalistic observation, systematic observation, or archival research was used.

Scenario
Researchers conducted an in-depth study with certain 9/11 victims to understand the psychological impact of the attack on the World Trade Center in 2001.

Researchers recorded the time it took drivers in parking lots to back out of a parking stall. They also measured the age and gender of the drivers, and whether another car was waiting for the space.

Contents of Craigslist personal ads in three major cities were coded to determine whether men and women differ in terms of their self-descriptions.

The researcher spent over a year meeting with and interviewing Aileen Wuomos, the infamous female serial killer who was the subject of the film Monster, to construct a psychobiography.

Researchers examined unemployment rates and the incidence of domestic violence police calls in six cities.

A group of researchers studied recycling behavior at three local parks over a 6-month period. They concealed their presence and kept detailed field notes.