ancestor node has been pruned, write N$/$A for and values.

$2)$ For question b$,$ note that there

are several reasons why the a$-$b pruning condition may not be triggered $($e$.$g$.$ condition never satisfied,

node never reached$).$

X: The third node in the third row $($children: $9,2,7,4)$

Y: The seventh node in the third row $($children: $1,7)$

Z: The last node in the third row $($children: $1,9,6,2)$

Answer the following $3$ Questions. Each Question has $4$ subquestions.