A 30 -year bond has an annual coupon rate of 6% for the first ten years, 7% for the next ten years, 8% for the last ten years, and matures at its par value of 100 . The bond is bought to produce an effective annual yield rate of 7%. Determine an expression for the price of the bond. (All interest functions are at 7% ) A 6a1010+7v10a10+8v20a10+(1.06)(1.07)(1.08)100 B) 100v20a10+a10 c) 100 D) 7a30+100v30 E ) 100+v20a10a30