When must a partnership file its return? Group of answer choices By the 15thBy the 15th day of the third month after the partnership's tax year-end and by the fifth month after the original due date if an extension is filed. By the 15thBy the 15th day of the fourth month after the partnership's tax year-end. By the 15thBy the 15th day of the third month after the partnership's tax year-end. By the fifth month after the original due date if an extension is filed and by the 15thby the 15th day of the fourth month after the partnership's tax year-end. By the fifth month after the original due date if an extension is filed