There shall be three methods of voting, each organization determining and stating in its bylaws which one of the methods of voting outlined herein shall be used. First, each owner of common stock may be allowed to vote his holdings of common stock, provided, however, that he shall not have a vote exceeding that which corresponds to twenty per cent of the total stock issued and outstanding by the organization; or second, any cooperative association may allow its members to vote according to their volume of business in proportion to the total volume transacted by each member through or with the organization during the fiscal year immediately preceding the annual or special meeting at which the vote shall be taken and each organization may determine the unit of volume which shall be used as a basis of computing the votes, such volume to be calculated as a basis of voting by units or value which each organization may determine in its bylaws; or, third, each member or common stockholder may be entitled to one vote.