图示无重直杆ACD在C处以光滑铰链与直角刚杆BC连接,若以整体为研究对象,以下四图中哪一个是正确的受力图。( )

A、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/153967528624993b7751f12e846cb80b0ce1e17f9e299.png" alt="上传图片">

B、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1539675297643532259df5ca7464ab999981bf6a9ab94.png" alt="上传图片">

C、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/153967531309951cebc3b33bd4473b67900c9997e4c73.png" alt="上传图片">

D、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/153967532608621129a6c65b34d26aefdce4297f1e9b4.png" alt="上传图片">