Use structural induction to show that$$l$($T$),$ the number of leaves of a full binary tree$$T$,$ is $1$ more than$$i$($T$),$ the number of internal vertices of$$T$,$ where an "internal vertex" is one with children.

Which is the correct basis step?

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Multiple Choice

l$($T$)=$i$($T$)=1$

For the full binary tree$$T$$consisting of just the root, the claim is true because$$l$($T$)=1$ and$$i$($T$)=0.$

For the full binary tree$$T$$consisting of one root and two leaves, the claim is true because$$l$($T$)=2,$i$($T$)=1,$ and $2=1+1.$

l$($T$)=$i$($T$)+1$