When we adjust the transportation scheme by closed-loop method, the rule is that the maximum value of transportation increasing in the cell equals the minimum value of the numeral cell to be reduced, which is to ( ).

When we adjust the transportation scheme by closed-loop method, the rule is that the maximum value of transportation increasing in the cell equals the minimum value of the numeral cell to be reduced, which is to ( ).
选项:make sure that the balance of production and selling can be realized.

make sure that the optimal scheme can be realized.

make sure that the traffic volume does not appear negative.

make sure that the freight cost can be reduced to a certain extent.