4. a) Construct a B-tree for the following set of key values: (3, 4, 5, 7, 9, 14, 15, 21, 22 and 23) Assume that the tree is initially empty and values are added in ascending order. Construct B-trees for the cases where the number of pointers that will fit in one node is 5. b) A database administrator can choose how many disks are organized into a Single RAID 5 array. What are the trade-offs between having fewer disks versus more disks, in terms of cost, reliability, performance during failure, and performance during rebuild