Which qualitative technique focuses on how users group different items?

The correct answer is card sorting, which is a qualitative technique specifically designed to understand how users organize and categorize different items. In card sorting exercises, participants are presented with a set of cards that represent items, features, or content, and they are asked to group these cards based on similarities or relationships that make sense to them. This process reveals users' mental models and can inform the design of information architecture, navigation structures, and more.

Card sorting is particularly beneficial because it offers insight into users' thought processes, helping designers create systems that are intuitive and user-friendly. By observing how users sort the cards, designers can identify shared patterns and preferences, leading to better-organized products that align with user expectations.

While focus groups gather qualitative feedback through discussion, they do not specifically focus on item grouping. Usability testing evaluates the effectiveness of a product's design by observing users as they interact with it, but it does not primarily assess how users categorize items. Surveys collect quantitative data but don't usually provide the depth of insight into item organization that card sorting offers. Thus, card sorting is the most suitable technique for understanding how users group different items.