Explanation:

Option B: For a Flexible exchange rate system to work, the inflow and outflow of foreign currency should be largely uninhibited. When this is severely curtailed, the system can’t work. This is because for the exchange rate to be determined, there must be free buying and selling of the domestic currency in the international market. CAC means inflow and outflow of foreign currency for the purpose of trade, remittances etc. is freely allowed. When CAC is stopped, the buying and selling of currency is stopped, and hence its value determination. Flexible exchange rate system becomes dysfunctional.

Option A, C and D: In rest of the options, this movement of currency is not stopped, and it continues, hence the flexible exchange rate system remains intact