Which one of the following statements about efficient portfolios is correct?

Any efficient portfolio will lie below the minimum variance portfolio when the expected portfolio return is plotted against the portfolio standard deviation.An efficient portfolio will have the lowest standard deviation of any portfolio consisting of the same two securities.Any portfolio mix consisting of only two securities will be an efficient portfolio.There are multiple efficient portfolios that can be constructed using the same two securities.There is only one efficient portfolio that can be constructed using two securities.