Quiz: Floyd-Warshall DP State

In Floyd-Warshall, the DP state is dist[k][i][j]: shortest path from $i$ to $j$ using only intermediate vertices from $\{0, 1, \ldots, k-1\}$. Why can you drop the $k$ dimension and use just dist[i][j]?

1. A.The $k$ dimension is always equal to $i$
2. B.When computing layer $k$, you only read from layer $k-1$, and in-place updates do not cause errors
3. C.Removing the $k$ dimension makes the algorithm faster
4. D.The $k$ dimension only affects the diagonal entries