What type of research refers to original data collected firsthand by a researcher?

The correct choice is primary research, which refers to original data collected firsthand by a researcher. This type of research is often conducted through various methods such as surveys, interviews, observations, and experiments. By gathering data directly from the source, researchers can ensure that the information is relevant and tailored to their specific study objectives.

Primary research is essential in fields like social science, where insights drawn from original sources can provide deeper understanding and context. This method stands in contrast to secondary research, where researchers analyze data that has already been collected and published by others. Tertiary research compiles and synthesizes information from primary and secondary sources, often to provide overviews or summaries, while quantitative research focuses specifically on numerical data and statistical analysis, which can be part of primary research but does not encompass all forms of it.