Explanation
Why Correct: Numismatics is the scientific study and analysis of coins, including their history, minting, metallurgy, and inscriptions. It is a crucial source for reconstructing the economic, political, and cultural history of ancient and medieval India, providing evidence for trade routes, dynastic chronologies, and monetary systems.
Distractor Analysis: Epigraphy is the study of inscriptions, typically carved on stone, metal, or other durable materials, and is distinct from the study of coins. Calligraphy is the art of beautiful handwriting, often seen in manuscripts and official documents. Coinography is not a standard academic term for the study of coins; it is a fabricated distractor.
Takeaway: The study of seals is called Sigillography, and the study of manuscripts is called Codicology or Palaeography (the study of ancient writing systems). These three disciplines—numismatics, epigraphy, and palaeography—are the primary auxiliary sciences used by historians to date and authenticate ancient Indian sources.