What action would violate a company's policy that prohibits personal social media use during business hours?

Engaging in personal social media use during business hours directly conflicts with a company's policy aimed at maintaining productivity and focus within the workplace. Posting to your timeline on Facebook is a clear example of using personal social media, which can distract employees from their work responsibilities and reduce overall efficiency.

The other options—checking work emails, collaborating with coworkers on a project, and scheduling a meeting on a work calendar—are activities that align with professional duties and contribute to workplace productivity. These actions involve utilizing work-related communication channels and tools that support the company’s operations, thereby adhering to the policies designed to promote an effective work environment.