What component connects related terms under broader groups?

The correct answer is that "Related Concepts" connects related terms under broader groups. This component is essential in organizing and categorizing information, as it helps to establish a hierarchical structure where specific terms can be grouped under general concepts. This structuring allows for a clearer understanding of how various topics relate to each other within a broader context.

In databases and information retrieval systems, relationships among concepts are vital for efficient searching and retrieval of information. By using related concepts, it enables users to navigate through information more intuitively, seeing not just isolated terms but also how they connect to other terms that share a thematic or contextual relationship.

In contrast, while keywords often serve as the main terms searched for, they do not inherently demonstrate the connections between related terms. Indexed terms are specific words or phrases assigned to content to facilitate better discovery but may lack the broader relational context. Primary terms typically denote the main focus of a topic without emphasizing the relationships with other related terms. Thus, "Related Concepts" specifically addresses the need for connecting terms under broader classifications, making it the most appropriate choice.