The correct answer is B. A means of communication
Step-by-step explanation:
The word "medium" is the singular form of the word "media" and refers to the means, tools or channels used to transmit information or to communicate with other people that include letters or printed materials, but also more modern means such as television radio or internet. These mediums are an essential point in the process of communication and usually evolve because they are related to social and historical processes and events. Therefore, a medium is a means of communication.