Bulletins, leaflets, circular letters, posters, fair, exhibitions, radio are the media of: 

Communication tools are commonly used to convey messages to large audiences. Understanding the type of communication these tools represent helps categorize the nature and purpose of the message being delivered

Key Points

• Bulletins, leaflets, circular letters, posters, fair, exhibitions, radio are the media of Mass Communication.
• Mass communication involves reaching a large audience through various channels.
• Bulletins, leaflets, posters, exhibitions, and radio are all tools that are used to disseminate information to a broad group of people, making them a key component of mass communication.

Hint

• Public communication: While public communication involves interactions with a large group, it is typically more focused on engaging with the public in specific settings, rather than using mass media tools.
• Official communication: This involves formal communication within organizations or institutions, often through official channels such as memos, reports, or meetings.
• Group communication: This refers to communication within a small group, focusing on direct interactions among a limited number of people, not mass media.

Hence, the correct answer is mass communication.