Answer: A. flyer; details describe problem and possible solutions.
Option A is the one that is most likely to be effective in this situation. A flyer is easy to distribute, so you can reach a large audience. Moreover, it tends to be small, which means that people are more likely to read it as the text will be very short and concise. Finally, it is a good idea to include both the problems and the solutions if you want to achieve collective action.