单项选择题
写递归算法，将二叉树中所有结点的左、右子树相互交换。StatusExchangeBiTree(BiTree&T){BiTreep;if(T){p=T->lchild;T->lchild=T->rchild;T->rchild=p;ExchangeBiTree(T->lchild);__________}returnOK;}
A.ExchangeBiTree(p);
B.ExchangeBiTree(T->rchild);
C.ExchangeBiTree(T->lchild->rchild)
D.ExchangeBiTree(T);