Quiz: LCA Distance

You know depth[u], depth[v], and depth[lca(u, v)]. Which formula gives the distance between $u$ and $v$?

1. A.depth[u] + depth[v] + depth[lca(u, v)]
2. B.depth[u]-depth[v]
3. C.2 * depth[lca(u, v)]-depth[u]-depth[v]
4. D.depth[u]+depth[v]-2 * depth[lca(u, v)]