Many economists doubt that G7 nations cannot "manage" rates because?

4 is correct. Example: The Swiss central bank has been trying hard to prevent an appreciation of the Swiss Franc (CHF): since the start of the crisis Switzerland has added around $100 billion, or 20% of GDP, to its foreign exchange reserves through interventions in the foreign exchange markets. And still, the CHF has still strengthened from 0.61 to 0.72 Euro.