以下用 BFS 查找特定值的节点，横线处应填入：
while (!q.empty()) {
TreeNode* current = q.front(); q.pop();
if (current->val == target) return current;
________ // 在此处填入代码
}
- A. if (current->left) q.push(current->left); if (current->right) q.push(current->right);
- B. if (current->left) q.pop(current->left); if (current->right) q.pop(current->right);
- C. if (current->left) q.front(current->left); if (current->right) q.front(current->right);
- D. if (current->left) q.push(current->right); if (current->right) q.push(current->left);
正确答案：A