State whether the following are True or False. Be sure to briefly explain your reasoning using written, graphical or mathematical arguments.

a. According to the Diamond-Dybvig model, the presence of banks in the financial system is always welfare improving because they can implement the optimal level of social insurance.

b. Suppose the world economy has two goods. If the law of one price holds for each of these goods, then the real exchange rate must equal one.

c. According to Helene Rey's "policy dilemma" a country might require international capital controls to have monetary independence, even when the exchange rate is floating.

plz answer a b c correct explaination

dont answer by pen paper