According to Miller groups can be classified as:

Answer: Option D

According to Miller, groups can be classified into two types: sanctioned and unsanctioned.

Sanctioned groups are those that are recognized and approved by society or institutions. They operate within the framework of social norms and rules.

Unsanctioned groups are those that exist outside of formal recognition and may not conform to societal expectations or institutional rules.

This classification helps to understand the role of groups in maintaining or challenging social order.