NO.PZ2023010401000162
问题如下：
In the classification of currency regimes, a currency board system (CBS) most likely differs from a fixed-rate parity system in that:
选项：
A.a CBS has a discretionary target level of foreign exchange reserves.
B.a CBS can peg to a basket of currencies but a fixed-rate system cannot.
C.the monetary authority within a CBS does not act as a traditional lender of last resort.
解释：
In a CBS, the monetary authority has an obligation to maintain 100% foreign currency reserves against the monetary base. It thus cannot lend to troubled financial institutions. As long as the country under a fixed-parity regime maintains its exchange peg, the central bank can serve as a lender of last resort.
中文解析：
在CBS中，货币当局有义务保持100%的外汇储备。因此，它无法向陷入困境的金融机构提供贷款。只要在固定汇率制度下的国家保持汇率挂钩，央行就可以充当最后贷款人。
B选项说的应该是什么制度呢
