Consider a B$+$tree index with Alternative $2$ for data entries.

The B$+$tree has $4$ levels $($i$.$e$.,$ the root, index level $1,$ index level $2,$ data entry level$)$ and the order $60$

$($i$.$e$.,$ each disk page has minimum $60$ and maximum $120$ index entries or data entries$).$ A search

key value k has at most $1000$ records and each disk page contains at most $50$ data records.

$1.$ If the B$+$tree is clustered, what is the maximum I$/$O cost to retrieve the data records

matching the search key value k