The correct answer is B) earned media.
The kind of media that the environmental group was aiming for was earned media.
An environmental group organizes a speaking event for a woman who speaks publicly about the negative health effects she experienced from drinking polluted water. The environmental group tried to get earned media.
Earned media is the media activity generated by customers, fans, clients, followers or publications by journalists. It is not paid advertisement, and it is not organized by a company or professional agents. In this case, a non-lucrative environmental group tries to get the word of mouth to promote the conference and get some good attendance.