10.

Which of the following statement is correct?

		In an economy that has four risky assets and NO risk-free asset, any portfolio on the mean-variance efficiency frontier is the best plausible portfolio
		In an economy that has four risky assets and a risk-free asset, any portfolio under the mean-variance efficiency frontier is the best plausible portfolio
		There is no arbitrage opportunity is an assumption of CAPM
		APT assumes investors are mean-variance optimizers