带下量多，色白清稀，腰酸多见于（）

A．脾阳虚证

B．寒湿困脾证

C．湿热蕴脾证

D．肝胆湿热证

E．肾气不固证

Suppose you have a three-security portfolio containing bonds A, B and C. The effective portfolio duration is 5.9. The market values of bonds A, B and C are $60, $25 and $80, respectively. The durations of bonds A and C are 4. 2 and 6.2, respectively. Which of the following amounts is closest to the duration of bond B（）

A. 9.0.

B. 1.4.

C. 7.1.