Quiz: MO's Complexity

In MO's algorithm, why does sorting by (l-block, r) give O((n+q)√n) total movement?

1. A.Because we visit each element exactly once
2. B.Because r moves O(n) per l-block, and l moves O(√n) per query
3. C.Because the queries are already sorted by r
4. D.Because we use binary search to find ranges