A necessary condition for international portfolio diversification to be beneficial is that The various national market returns exhibit correlations that are non-unity. The various national market returns are perfectly positively correlated. The various national market returns are perfectly negatively correlated. The various national market returns exhibit high correlation The various national market returns exhibit low correlation A necessary condition for international portfolio diversification to be beneficial is that The various national market returns exhibit correlations that are non-unity. The various national market returns are perfectly positively correlated. The various national market returns are perfectly negatively correlated. The various national market returns exhibit high correlation The various national market returns exhibit low correlation