How many stacks are required for the evaluation of postfix expression?

Question $8$ options:

Three

Two

Four

One

Question $9(1$ point$)$

You must implement a sorting algorithm to sort log error file in a large busy server by time. This sorting task is done at night when there is little activity. The nature of log error files is that they should theoretically be sorted by time, but this cannot be guarantee since the server may prioritize other tasks over error reporting. Which sorting algorithm is best to use in this case

Question $9$ options:

Heap Sort

Merge Sort

None of the answers are correct

Radix Sort

Quick Sort