根据乙肝表面抗原的抗原性进行分型的意义是（）

A.有助于流行病学调查

B.判断预后

C.确定传播途径

D.制定治疗方案

E.确定基因型

Biggs, Inc., holds a bond portfolio that is, on average, trading below par value. They have faced some cash flow problems of late and have used the bond interest payments for operating expenses. The bonds are callable. Given the current situation, Biggs faces which types of risk（）

A. Interest rate risk. 

B. Interest rate risk and reinvestment risk. 

C. Interest rate risk and call risk.