(1) Any public utility receiving from the commission any blanks with directions to fill the blanks shall cause the blanks to be properly filled out so as to answer fully, specifically, and correctly every question therein propounded.
(2) Answers shall be verified under oath by the president, secretary, superintendent, or general manager of the public utility and returned to the commission at its office within a reasonable time, or within the period fixed by the commission.
(3) In case the public utility is unable to answer any questions, it shall give a good and sufficient reason for such a failure.