Which of the Following Statements Is Most Correct

Which of the following statements is most correct?

A) Holding foreign stocks in one's portfolio affords greater diversification potential because the stock market returns in different countries are not perfectly correlated.
B) Exchange rate risk could be a significant issue if a portfolio is internationally diversified, particularly when shares from only a few countries are held.
C) A world market index and a global risk-free rate should be used to evaluate internationally diversified portfolios. These can be proxied by using the Morgan Stanley Capital International global index and the required return on long-term United Nations bonds.
D) All of the statements above are correct.
E) Only statements a and b are correct.