Although Tariff and Quota Protections for China Auto Imports Were

Although tariff and quota protections for China auto imports were very costly to consumers, which of the following was a benefit?

A) Auto prices, compared with other prices in the economy, actually fell.
B) Auto consumption skyrocketed, but there were environmental effects.
C) Firms that were involved in joint ventures were able to "learn" and to significantly lower their costs.
D) China's government realized it had to keep its hands off entrepreneurial concerns.