How to calculate B when there is many risk free?

Use the following information to answer the question below. Year 2008 2009 2010 2011 Risk-free Return 1.75% 1.25% 1.25% 1.50% Market Return 7.50% -30.00% 9.50% 11.50% PE-Waters Return 4.50% -31.50% 6.00% 5.50% Using the historical average excess retums and historical volatilities of both PE- Waters and Market portfolio that you can calculate from the information above, your estimate of PE-Waters' Beta is closest to: A) 2.065 0.384 0.927 1.122 D)