Quiz: LCA via Binary Lifting

In the LCA algorithm, after equalizing depths you jump both nodes upward in decreasing powers of $2$. Why do you skip a jump when up[u][k] == up[v][k]?

1. A.Because you want to stop just below the LCA, not at or above it
2. B.Because you have found the LCA at that point
3. C.Because equal ancestors mean the nodes share a subtree
4. D.Because the table entry is invalid at that level