Final answer:
The Marketing and Public Relations Departments are primarily responsible for managing a company's social media activities, focusing on advertisement strategies and public image, respectively.
Step-by-step explanation:
Generally, the responsibility for a company's social media activities tends to fall within the scope of the Marketing Department and the Public Relations Department.
The Marketing Department is involved in strategizing advertisements and promoting products or services, which naturally extends to managing social media as a marketing channel.
Meanwhile, the Public Relations Department focuses on managing the company's image and relationships with the public, which includes prompt and effective communication through social media platforms.
While the IT Department can provide support in terms of technology and infrastructure needed for social media activities, it is not commonly responsible for the content or strategy.
The Human Resources Department might use social media for recruiting and employer branding efforts but does not usually handle general company social media profiles.