Quiz: Matching States

In the tree matching DP, you track dp[u][0] and dp[u][1]. What do these states represent?

1. A.dp[u][0]: u is not selected as a node. dp[u][1]: u is selected as a node.
2. B.dp[u][0]: u does not use an edge to its parent. dp[u][1]: u uses an edge to its parent.
3. C.dp[u][0]: subtree of u has $0$ matched edges. dp[u][1]: subtree has $1$.
4. D.dp[u][0]: u is a leaf. dp[u][1]: u is internal.