What is mass communication?

messages that must be delivered with care due to their emotional weight
messages that are delivered in a church or during a religious service
the imparting of wisdom or educational knowledge, to a group such as a class
the imparting of information on a large scale, to a wide range of people

The imparting of information on a large scale, to a wide range of people is the correct answer for what mass communication is. It involves the transmission of messages through various forms of media to reach a large audience.