This topic investigates the foreign exchange management system of current account. Current account foreign exchange income is subject to the willingness to settle foreign exchange; Option A is wrong to say "compulsory foreign exchange settlement system". Current account usually refers to the frequent transactions in a country or region's foreign exchanges, including trade balance, service balance, income and current transfer. Income includes employee compensation and investment income; Option B is wrong to say "excluding investment income". Current account foreign exchange expenditure is based on valid documents and does not need approval; Option c says "for approval" is wrong.