The strange situation paradigm is often used to assess the attachment of one- to two-year-old children to their mothers. The mother and child enter a room that is equipped with a two-way mirror. Then, a stranger walks into the room

Following this the mother leaves her child with the stranger. Lastly, the mother returns to the room. Throughout the procedure, a researcher observes and records the interactions between the mother and child. This is an example of a ___________ study.
a. field c. ethnographic
b. laboratory d. ground

b