Question 4 A B-tree index has the height of 4 (including the root), stored on disk using Alternative (2) for data entries. The number of data entry pages is 1,000 and the number of data record pages is 100,000, and the number of data records is 10M. Suppose that the search key value k=5 matches 10% of data records in the file. What is the I/O cost (in page) of retrieving the records matching the search key k=5 using the index under the following two cases: 1) The index is clustered. 2) The index is unclustered. Explain steps and show you work. Note: Alternative 2 for data entries =