The benefit of using to communicate a business's CSR efforts to the public is that it allows companies to reach broad and diverse groups directly in a low-cost, efficient way.

Social Media.

Explanation:

Social Media:  It is technology-based interactive media that allow individual or organization to share an idea, information, etc to the whole world in real-time. It is effective mean of marketing or information-sharing platform which give the response in quick time. Organizations use this media to introduce their goods & services, their promotional campaign, CSR activity, customer feedback, etc as response time is very less than any other medium of communication and at the lowest cost.

In the given case, the Business´s CSR effort has been communicated to the public of vast range directly at a low cost in an effective way, therefore, they have used Social media to communicate.

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