【单选题】
如下图所示,列出节点1的基尔霍夫电流方程为()<br /> <img src="https://nimg.ppkao.com/2019-05/tangling/2019051410175664603.jpg?sign=e480c12ced06687b3b0c4daf04fed17a&t=62d762e8" />
A、Ib+Ia-I1=0
B、Ib-Ia+I1=0
C、Ib-Ia-I1=0
D、Ib+Ia+I1=0