Final answer:
In the foreign exchange market, four groups of participants demand and supply currency through financial institutions.
Step-by-step explanation:
In the foreign exchange market, there are four main groups of participants who demand and supply currency: (1) firms involved in international trade, (2) tourists visiting other countries, (3) international investors buying ownership or part-ownership of foreign firms, and (4) international investors making financial investments without ownership. These participants are not directly involved in person-to-person currency trades, but rather transact through financial institutions.