Hedging refers to buying and selling the same commodity in the spot market and the futures market at the same time in the same amount but in the opposite direction, that is, selling or buying the same amount of futures in the futures market while buying or selling the spot. After a period of time, when the price changes gain or lose in spot trading, the losses in futures trading can be offset or compensated, so item A is correct; Financial swap is a transaction form in which two or more traders exchange a series of cash flows within the agreed time according to the agreed conditions, so item B is wrong; Investment refers to the economic behavior of a specific economic entity to invest a sufficient amount of funds or physical currency equivalents in a certain field in order to obtain income or capital appreciation in the foreseeable future, so item C is wrong; Risk-free arbitrage is a financial tool, which means investing capital (usually currency) in a group of foreign exchange, agreeing on a forward exchange rate, and converting foreign exchange into local currency according to the established exchange rate after obtaining the deposit income of foreign exchange, so as to obtain the income higher than the domestic deposit interest rate, that is, hedging and locking the exchange rate at the same time, which is called risk-free arbitrage, so item D is wrong. So the answer is a.