What Is the Role of a Speculator in Foreign Exchange

What is the role of a speculator in foreign exchange markets?  

A)  to buy foreign currency, hoping to profit by selling it at a higher exchange rate at some later date 
B)  to earn illegal profit by manipulating foreign exchange 
C)  to cause differences in exchange rates in different geographic markets 
D)  to simultaneously buy large amounts of a currency in one market and sell it in another market