Quiz: Kuhn's Algorithm Complexity

In Kuhn's algorithm, you run DFS from each unmatched left node to find augmenting paths. For a bipartite graph with $n$ left nodes and $m$ edges, what is the time complexity?

1. A.$O(n \times m)$
2. B.$O(n + m)$
3. C.$O(n^2 \times m)$
4. D.$O(m \log n)$