图示对称结构中，I点处的弯矩为下列何值？

• A.0
• B.<img src="https://timg.fentiku.com/97/2016/12/22/dfQnJXvgyJ.png" title='dfQnJXvgyJ.png' alt='dfQnJXvgyJ.png'/>
• C.qa<img src="https://timg.fentiku.com/97/2016/12/22/lojW5MwtUZ.png" title='lojW5MwtUZ.png' alt='lojW5MwtUZ.png'/>
• D.<img src="https://timg.fentiku.com/97/2016/12/22/ryMJnxqEwu.png" title='ryMJnxqEwu.png' alt='ryMJnxqEwu.png'/>

正确答案：B