【单选题】
图2所示杆件的矩形截面,其抗弯截面模量Wz为()<br/> <img src="https://nimg.ppkao.com/2018-07/chenfang/2018072010462499721.jpg?sign=08b17cd473d94bb0be83c7320d675a23&t=62d20f75"/><br/><img src="https://nimg.ppkao.com/STUploads/2020/12/13/Images/61e413ac3a7548f7b17ece49df4bcba3.png?sign=38bb4101a6a001615046481a003329ae&t=62d20f75"/>
A、A
B、B
C、C
D、D