Quiz: D&C Complexity

In D&C DP optimization, why is total time O(n^2 log n) instead of O(n^3)?

1. A.Monotonicity allows skipping most split points
2. B.Each recursion level partitions the search space, and total split points per level is O(n)
3. C.Binary search finds optimal split in O(log n)
4. D.We use memoization to avoid recomputation