Colton is a portfolio manager at Austin Associates. For all his clients, Colton manages portfolios that lie on the Markowitz efficient frontier. Wilson asks Mary Regan, CFA, a managing director at Austin, to review the portfolios of two of his clients, the Eagle Manufacturing Company and the Rainbow Life Insurance Co$.$ The expected returns of the two portfolios are substantially different. Regan determines that the Rainbow portfolio has a higher return and therefore concludes that the Rainbow portfolio must be superior to the Eagle portfolio.

Do you agree or disagree with Regan's conclusion that the Rainbow portfolio is superior to the Eagle portfolio? Justify your response with reference to the capital market line.