The research which is exploring new facts through the study of the past is…

Concept: Research is often classified by the approach or purpose it serves. Historical research is the systematic method of examining and analysing primary and secondary sources — documents, records, artifacts, and testimonies — from the past in order to reconstruct events, verify claims, and often bring to light facts about the past that were not previously known or documented.

Application: The stem describes research that ‘explores new facts through the study of the past’ — this is exactly the defining purpose of historical research: it systematically investigates past events and sources to establish or discover facts, rather than merely restating what is already known.

Cross-check — contrasting the other options by what each actually is:

• Philosophical research: examines concepts, values, and reasoning through logical analysis and argumentation rather than empirical investigation of past events.

• Mythological research: studies myths, legends, and traditional narratives to understand cultural or symbolic meaning, not to establish verified facts about the past.

• Content analysis: a systematic method for analysing the content of documents, texts, or media for patterns and themes; it is a technique that can be applied within many types of research, not a genre defined by uncovering facts about the past.

Hence, the type of research described in the stem is historical research.