简支工字钢梁在均布荷载作用下绕强轴的弯矩设计值为M=89．2kN·m，钢材牌号为Q235，f=215N／mm，抗弯强度验算时不考虑截面塑性发展系数，至少应选用下列哪一种型号的工字钢?

• A.工25a(净截面模量401．4cm<img src="https://timg.fentiku.com/101/2016/10/21/BnsiFXkj2I.png" title='BnsiFXkj2I.png' alt='BnsiFXkj2I.png'/>)
• B.工25b(净截面模量422．2cm<img src="https://timg.fentiku.com/101/2016/10/21/DRp0XWhCfa.png" title='DRp0XWhCfa.png' alt='DRp0XWhCfa.png'/>)
• C.工28a(净截面模量508．2cm<img src="https://timg.fentiku.com/101/2016/10/21/6JZCkFcieX.png" title='6JZCkFcieX.png' alt='6JZCkFcieX.png'/>)
• D.工28b(净截面模量534．4cm<img src="https://timg.fentiku.com/101/2016/10/21/941aAd22Ox.png" title='941aAd22Ox.png' alt='941aAd22Ox.png'/>)

正确答案：B