在结构图中，钢结构熔透角焊缝表示方法，下列哪一种形状是正确的?

• A.<img src="https://timg.fentiku.com/101/2016/10/21/gC53d9kNTa.png" title='gC53d9kNTa.png' alt='gC53d9kNTa.png'/>
• B.<img src="https://timg.fentiku.com/101/2016/10/21/Ev3o8ekJmT.png" title='Ev3o8ekJmT.png' alt='Ev3o8ekJmT.png'/>
• C.<img src="https://timg.fentiku.com/101/2016/10/21/xq6rqpqzAo.png" title='xq6rqpqzAo.png' alt='xq6rqpqzAo.png'/>
• D.<img src="https://timg.fentiku.com/101/2016/10/21/x4KITXGDAL.png" title='x4KITXGDAL.png' alt='x4KITXGDAL.png'/>

正确答案：D