The Gupta Empire is often noted for its relatively decentralized system of governance and the promotion of trade, culture, and education. The emperor would maintain power through a combination of encouraging local governance, promoting trade, and fostering a rich cultural environment.
Among the options provided, the most suitable answer would be:
D. through enriching subjects through trade.
While the Gupta emperors maintained authority and could exert control, they also facilitated a flourishing economy and cultural development that enriched their subjects through trade and intellectual achievement.