निम्नलिखित में से कौन सा गैर-संभाव्यता प्रतिचयन (non-probability sampling) तकनीक का एक प्रकार है?

To establish and analyze cause-and-effect relationships (causality), researchers primarily rely on:

Match List-I (Type of Research) with List-II (Description): List-I: a. Fundamental Research b. Longitudinal Research c. Descriptive Research d. Qualitative Research List-II: i. Research carried out over extended periods of time on the same subjects ii. Research aimed at expanding basic knowledge, theories, and skills iii. Research based primarily on non-numerical qualitative observations/narratives iv. Fact-finding inquiry describing current state of affairs and social events Choose the correct code: