Final answer:
The example of a period cost is a manager's salary for work that is done in the corporate head office.
Step-by-step explanation:
A period cost is a cost that is not directly associated with the production of goods or services. It includes expenses that are incurred in a particular period of time and cannot be traced back to a specific product or service. Based on the given options, the example of a period cost is option a) A manager's salary for work that is done in the corporate head office. This cost is not directly related to the production process and is incurred regardless of the level of production or sales. It is considered a period cost because it is associated with a specific period of time, usually a month or a year.