Deliberate, long-term media campaigns such as Smokey the Bear, which began in 1944 and is still with us today, are examples of ads used by nonprofit organizations to educate the public. They are commonly known as:a. messages to the masses. b.mass media services. c.public service announcements. d.fireside chats.

Public service announcement.

Explanation:

A public service announcement is a message in the public interest that is disseminated without charge and with the aim of raising awareness, changing public attitudes and the behavior of people towards a social issue.

In the United Kingdom, public service announcement is called public information films. The common topics discussed in public service announcements are safety and health related topics such as issues relating to obesity, gambling etc.