B+ Trees are considered BALANCED because
(A) the lengths of the paths from the root to all leaf nodes are all equal.
(B) the lengths of the paths from the root to all leaf nodes differ from each other by at most 1.
(C) the number of children of any two non-leaf sibling nodes differ by at most 1.
(D) the number of records in any two leaf nodes differ by at most 1.
Explanation: In both B Tree and B+ trees, depth (length of root to leaf paths) of all leaf nodes is same. This is made sure by the insertion and deletion operations.
In these trees, we do insertions in a way that if we have increase height of tree after insertion, we increase height from root. This is different from BST where height increases from leaf nodes.
Similarly, if we have to decrease height after deletion, we move the root one level down. This is also different from BST which shrinks from bottom.
The above ways of insertion and deletion make sure that depth of every leaf node is same.
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