You are a bond portfolio manager and have $1.2 million that you will invest for 3 years. You have an obligation due in 3 years and you want to immunize your portfolio against interest rate risk over this horizon. You use the $1.2 million to invest in two zero coupon bonds: a 4 year bond and a 1 year bond. How much money should you invest in the 4 year bond?

A) $600,000

B) $1.2 million

C) $400,000

D) $800,000

E) $900,000