Assume arr2 is declared as a two-dimensional array of integers. which of the following segments of code successfully calculates the sum of all elements arr2? int sum = 0; for(int j = 0; j < arr2.length; j++) { for(int k = 0; k < arr2[j].length; k++) { sum += arr2[k][j]; } } int sum = 0; for(int j = arr2.length − 1; j > = 0; j−−) { for(int k = 0; k < arr2[j].length; k++) { sum += arr2[j][k]; } } int sum = 0; for(int[] m : arr2) { for(int n : m) { sum += n; } }