试题选项中图形符号表示用于测量功率的仪表是(____)。
A<img src="/tupian/shandong/dinghongjian/dinghongjian17.jpg"/>
B<img src="/tupian/shandong/dinghongjian/dinghongjian18.jpg"/>
C<img src="/tupian/shandong/dinghongjian/dinghongjian19.jpg"/>
D<img src="/tupian/shandong/dinghongjian/dinghongjian20.jpg"/>