边长为a的正方形侧面BB1C1C对角线上作用一力<img src="/Image1/7d/7da4dd57790ebd5cbe31c9e6503df4f7.png" />，则力<img src="/Image1/7d/7da4dd57790ebd5cbe31c9e6503df4f7.png" />对<img src="/Image1/49/49b305e0adf7ff411693581118f65f72.png" />，<img src="/Image1/91/912a862f557820b399eb43502d614682.png" />，<img src="/Image1/4c/4c2ede96c769f420c08ba949764607f8.png" />三轴之矩为（）。 <img src="/Image1/c5/c5bb2ab263c5f8aa768c12ae60a49157.png" /><br>A:<img src="/Image1/72/72a5d27a42037ecd5601acd6a6a6f47d.png" /><br>B:<img src="/Image1/ca/ca7605def60e552da76c03e74a89cf0f.png" /><br>C:<img src="/Image1/d7/d746e3b0274eb6c3fc536af242e79faa.png" /><br>D:<img src="/Image1/53/53c4a87c002192d00ab93f8bec8430c6.png" />