Quiz: Counting Paths in a DAG

You count paths from node $1$ to node $n$ in a DAG. For node $v$, you compute paths[v] = sum of paths[u] for all predecessors $u$ of $v$. Why must you process nodes in topological order?

1. A.Because topological order minimizes memory usage
2. B.Because the count depends on which topological order you choose
3. C.Because it ensures paths[u] is finalized before you use it to update paths[v]
4. D.Because reverse topological order gives a different count