The B$+$Tree shown below is invalid. That is$,$ its nodes violate the correctness

properties of $B+$ Trees. If the tree is invalid, select the property that is violated by

each node. If the node is valid, then select 'None'.

Note: If a node's subtrees are not the same height, the balance property is violated

at that node only.

Which property is violated by Leaf $1?$

Key values are in the right order.

Each non$-$leaf node is at least half$-$full.

$B+$ tree is balanced.

Internal nodes guide the search.

None.