Bubble sort each row

#include <stdio.h>
#define ROWS 4
#define COLS 6

int main()
{
    int temp,i,j,k,arr[ROWS][COLS] = {6,5,4,3,2,1,  16,15,14,13,12,11,   26,25,24,23,22,21,   36,35,34,33,32,31};//

    for(i=0;i<ROWS;i++)//i- row number. what is good name for it?
    {
        for(j=0;j<COLS-1;j++)//j- variable used for iteration count, nothing to do with
            //row or column. what is good name for it?
        {
            for(k=0;k<COLS-1;k++)//k-column number. what is good name for it?
            {
                if(arr[i][k]>arr[i][k+1])
                {//swaps arr[i][k] && arr[i][k+1]
                    temp = arr[i][k];
                    arr[i][k]= arr[i][k+1];
                    arr[i][k+1]= temp;
                }
            }//end for k
        }//end for j
    }//end for i

    for(i=0;i<ROWS;i++)//prints new array
    {
        for(j=0;j<COLS;j++)
        {
            printf("%d\t",arr[i][j]);
        }
        printf("\n");
    }

    return 0;
}