Final answer:
The theory of 'postmemory' refers to the process where the subsequent generation inherits and forms second-hand memories of trauma experienced by the previous generation.
Step-by-step explanation:
The theory of 'postmemory' refers to option 3, a process of transmission whereby the generation that follows historical trauma acquires second-hand memories recounted by the generation that experienced trauma. This concept pertains to how individuals who did not directly experience a traumatic event, such as war or genocide, can still exhibit strong emotional responses and form memories based on the stories, images, and behaviors they inherit from the actual survivors.
Postmemory is a significant psychological and cultural phenomenon, as it affects how memories are constructed within families and communities, influencing collective memory. It also shows the powerful impact of traumatic events that can transcend the original generation and continue to affect subsequent generations.