JSFiddle - React, Tailwind, and code Playground

JavaScript

function largestOfFour(arr) {
	var largest = 0,
        largestOrigin = [];
    
    for(var i = 0; i < arr.length; i++){ 
        for (var j = 0; j < arr[i].length; j++) {
            if(arr[i][j] > largest){
                largest = arr[i][j];
                largestOrigin = arr[i];
            }
        }
    }
    return largestOrigin;
}

  document.body.innerHTML=(largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]));