Which of the following methods is used to study the diversity of human cultures in their particular cultural settings?

The correct option is Ethnography.

Explanation:
Ethnography is a qualitative research method central to anthropology and sociology. It involves the immersive, hands-on study of people and cultures in their natural, particular cultural settings.

Unlike methods that rely on external databases or controlled environments, an ethnographer participates directly in the daily lives of the subjects (often referred to as participant observation) to observe behaviors, rituals, social interactions, and beliefs first-hand. This immersive approach allows researchers to gain a rich, detailed, and holistic understanding of the diversity of human cultures from the perspective of the community members themselves.