Which of the following constitutes primary data?

The correct answer is focused on the nature of primary data, which is defined as data collected firsthand by the researcher for a specific purpose or study. This type of data is original and directly pertains to the research question being investigated. The primary goal is to gather information tailored to the unique parameters of the research, ensuring that the findings are directly applicable and relevant.

In contrast, the other options describe secondary data or data derived from existing sources. For instance, published sources refer to data that has already been analyzed and presented by others, whereas literature reviews compile and synthesize previously collected research, which again does not reflect original research efforts. Data interpreted from secondary sources also relies on existing research rather than fresh data collection, which highlights the distinction that primary data represents original work initiated by the investigator. Thus, the selection of data gathered directly by the researcher distinctly identifies it as primary data.