Explanation:

- The concept of "vertical group" refers to social groups that are organized hierarchically, often including people from different social classes or statuses.

- Option 1: Park - Robert E. Park was a sociologist but is not known for giving the concept of vertical groups.

- Option 2: Miller - Miller is not associated with the concept of vertical group.

- Option 3: Ginsberg - Ginsberg is credited with introducing the idea of vertical and horizontal groups in sociology.

- Option 4: Bogardus - Bogardus contributed to group dynamics but not specifically the vertical group concept.

Correct Answer: Option 3: Ginsberg