刚架的支座a产生沉陷△，则下列弯矩图，正确的是( )。

• A.<img src="https://timg.fentiku.com/97/2016/12/22/23xhCx3NGJ.png" title='23xhCx3NGJ.png' alt='23xhCx3NGJ.png'/>
• B.<img src="https://timg.fentiku.com/97/2016/12/22/CfgLwC8yPT.png" title='CfgLwC8yPT.png' alt='CfgLwC8yPT.png'/>
• C.<img src="https://timg.fentiku.com/97/2016/12/22/7wT3H08qc1.png" title='7wT3H08qc1.png' alt='7wT3H08qc1.png'/>
• D.<img src="https://timg.fentiku.com/97/2016/12/22/9u6t1FmoDK.png" title='9u6t1FmoDK.png' alt='9u6t1FmoDK.png'/>

正确答案：B