The Rigvedic economy was predominantly pastoral, and cattle represented its principal form of wealth. Agriculture was known and practiced, but it became more extensive and central during the Later Vedic period. Pastoralism (cattle rearing) fits that evidence because it matches the specific chronology, agency and function contained in the question. A comparison with the alternatives is useful: Trade, Agriculture and Industry are genuine historical terms or names, but each belongs to a different office, patron, text, region or sequence. The compact memory link is therefore Pastoralism (cattle rearing) together with the factual context above, not the isolated option letter.