What would be the output? (Array sum problem)

@Yomesh Gupta
function sum(first, ...middle, last) {
  return first + middle.reduce((acc, num) => acc + num, 0) + last;
}

console.log(sum(1, 2, 3, 4, 5));
Option 1
15
Option 2
undefined
Option 3
NaN
Option 4
Uncaught Error