Answer:
B. To hear about an important issue.
Step-by-step explanation:
Greenpeace is a famous NGO (non-governmental organization) that was founded in 1971. Greenpeace goal is to protect the natural environments of the planet, as well as its biodiversity. Some of its activities involve working against climate change, deforestation, overfishing and commercial whaling. People who go to a Greenpeace rally most likely want to hear about one of these important issues, and learn about what can be done to fix it.