图示结构，P位置处梁的弯矩为下列何值？

• A.0
• B.<img src="https://timg.fentiku.com/97/2016/12/22/1b8IgnKZG2.png" title='1b8IgnKZG2.png' alt='1b8IgnKZG2.png'/>
• C.<img src="https://timg.fentiku.com/97/2016/12/22/DrEx9V0au9.png" title='DrEx9V0au9.png' alt='DrEx9V0au9.png'/>
• D.Pa

正确答案：B