D08 Answer

int findMax( int x[][NUMCOLS], int nrows )
{
  int r, c;
  int max = x[0][0] ;
  
  for ( r=0; r<nrows; r++ )
    for ( c=0; c<NUMCOLS; c++ )
      if (x[r][c] > max ) max = x[r][c] ;
      
  return max;
}

Comment: Notice how max is initialized. Setting max to zero would not work.