Answer:
an independent contractor
Step-by-step explanation:
An independent contractor is any person or business or organization that gives services and goods in a written contract or sometimes a verbal agreement also. Unlike the employees, independent contractors does not work on a regular basis for the employer but he or she works as required, when they are subjected to the law of agency.
In the context, Nia hires O'Reilly as an independent contractor to clean the carpets of her dress shop and gives her instruction what to clean and when to clean.