The following shall constitute employees in private employment and their employers subject to the provisions of this law:
(1) A person performing service in the course of the trade, business, profession or occupation of an employer.
(2) A person, including a minor, whether lawfully or unlawfully employed, in the service of an employer under any contract of hire or apprenticeship, express or implied, and all helpers and assistants of employees whether paid by the employer or employee, if employed with the knowledge, actual or constructive, of the employer.
(3) An officer of a corporation.
(4) “Employment,” in the case of private employers, includes employment only in that trade, business, profession or occupation which is carried on by the employer and also includes any of the pursuits specified in section 72-212, Idaho Code, when the employer shall have elected to come under the law as provided in section 72-213, Idaho Code.