The Straightforward Generalization of the Simple CAPM to International Stocks

The straightforward generalization of the simple CAPM to international stocks is problematic because __________.

A) inflation risk perceptions by different investors in different countries will differ as consumption baskets differ
B) investors in different countries view exchange rate risk from the perspective of different domestic currencies
C) taxes, transaction costs and capital barriers across countries make it difficult for investor to hold a world index portfolio
D) all of the above
E) none of the above.