Foreign Exchange Swaps Are Best Described As

Foreign exchange swaps are best described as:

A) the right but not the obligation to buy or sell a currency by an agreed future date at an agreed price.
B) a contract in which one currency is exchanged for another at a price set now and delivered in more than two days' time.
C) a contract for the simultaneous buying and selling of one currency in exchange for another at various value dates.
D) buying a currency and then reversing the position by selling a short time afterwards.