Experimental studies are used to answer

A. Mixed research method: Mixed methods research combines both qualitative and quantitative approaches within the same study design. A one-to-one interview by itself does not constitute mixed methods unless it is paired with quantitative tools such as surveys or statistical analysis. Therefore, an individual in-depth interview alone does not represent a mixed research design.

B. Qualitative research method: One-to-one interviews are a hallmark of qualitative research because they explore participant perspectives, lived experiences, meanings, and social contexts. This method allows for open-ended questioning, probing, and rich narrative data collection. The goal is depth of understanding rather than numerical measurement or statistical inference.

C. Quantitative research method: Quantitative research focuses on measurable variables, numerical data, and statistical analysis. Structured questionnaires with fixed responses may be quantitative, but in-depth one-to-one interviews aim to gather descriptive, non-numerical data. The emphasis on detailed experiences aligns with qualitative methodology rather than quantitative design.

D. All of the above: Because one-to-one interviews are fundamentally qualitative in nature unless integrated into a broader mixed-methods framework, they do not simultaneously represent all research approaches. The method itself is most directly aligned with qualitative inquiry.

The alternative hypothesis (H₁) is a statement that proposes a relationship or effect that the researcher expects to find in the study. It is formulated based on theory, prior evidence, or a research question and serves as the basis for statistical testing. While it is assumed to be plausible, it has not yet been proven; the purpose of hypothesis testing is to evaluate whether the data provide sufficient evidence to support or reject it.