为什么选C 能解释一下题目和C吗

NO.PZ2023061903000052 问题如下 Q. Whiof the following tra restrictions is likely to result in the greatest welfare loss for the importing country? A.A tariff B.import quot C.A voluntary export restraint C is correct. With a voluntary export restraint, the priincrease incerestricting the quantity of imports (= quota rent for equivalent quota = tariff revenue for equivalent tariff) accrues to foreign exporters or the foreign government.在自愿限制出口的情况下，由于限制进口数量而引起的价格上涨(=等值配额的配额租金=等值关税的关税收入)归外国出口商或外国政府所有。 B、C都存在因为价格提高，社会福利产生损失的情况

NO.PZ2023061903000052 问题如下 Q. Whiof the following tra restrictions is likely to result in the greatest welfare loss for the importing country? A.A tariff B.import quot C.A voluntary export restraint C is correct. With a voluntary export restraint, the priincrease incerestricting the quantity of imports (= quota rent for equivalent quota = tariff revenue for equivalent tariff) accrues to foreign exporters or the foreign government. 为什么c比b损失的welfare更多？

NO.PZ2023061903000052问题如下Q. Whiof the following tra restrictions is likely to result in the greatest welfare loss for the importing country?A.A tariffB.import quotaC.A voluntary export restraintC is correct. With a voluntary export restraint, the priincrease incerestricting the quantity of imports (= quota rent for equivalent quota = tariff revenue for equivalent tariff) accrues to foreign exporters or the foreign government.b是什么 老师可以一下吗

NO.PZ2023061903000052问题如下Q. Whiof the following tra restrictions is likely to result in the greatest welfare loss for the importing country?A.A tariffB.import quotaC.A voluntary export restraintC is correct. With a voluntary export restraint, the priincrease incerestricting the quantity of imports (= quota rent for equivalent quota = tariff revenue for equivalent tariff) accrues to foreign exporters or the foreign government.可以一下tariff么，为什么不选A