Recursive 2D Array Traversal

What is the output produced when the following program is executed?

public class TransposePrint {
    public static void printTranspose(int[][] arr, int col, int row) {
        if (col == arr[0].length) return;
        if (row == arr.length) {
            System.out.println();
            printTranspose(arr, col + 1, 0);
            return;
        }
        System.out.print(arr[row][col] + " ");
        printTranspose(arr, col, row + 1);
    }
    public static void main(String[] args) {
        int[][] mat = { {1, 2, 3}, {4, 5, 6} };
        printTranspose(mat, 0, 0);
    }
}