Consider the lower bound proof which shows that no comparison$-$based sorting algorithm can function in less than nlogn time. In the proof, a "decision tree" model of a generalized sorting algorithm is shown. Why is it a binary tree? $($Meaning each node has at most two children, never more.$)$

It's because there are two arrays in the lower bound proof.

It's because mergesort divides the input in half.

It's because it ensures the tree has width $n($number of nodes$).$

It's because sorting algorithms must check if one element is less than another $($a boolean result$).$