There are four Vedas: Rigveda, Samaveda, Yajurveda and Atharvaveda. They should not be confused with the six Vedangas, which are auxiliary disciplines for studying and applying Vedic knowledge. Four fits that evidence because it matches the specific chronology, agency and function contained in the question. A comparison with the alternatives is useful: Six, Five and Three are genuine historical terms or names, but each belongs to a different office, patron, text, region or sequence. The compact memory link is therefore Four together with the factual context above, not the isolated option letter.