What kind of source involves an interpretation of a secondary source?

A tertiary source is indeed an interpretation or distillation of information from secondary sources. Tertiary sources compile and summarize information for easy access and reference, often providing an overview of a topic. Examples include encyclopedias, dictionaries, and indexes, which synthesize material from primary and secondary sources to present a broad understanding without the original context or detailed analysis present in the secondary sources.

In contrast, primary sources are original materials, such as research articles reporting new data or firsthand accounts, while secondary sources interpret and analyze primary data, offering more in-depth analysis. Quaternary sources are less common and usually refer to collections or databases of sources or metadata about secondary and tertiary sources. Hence, the tertiary source's role in summarizing and interpreting information makes it the correct choice in this context.