Option B. Going with option A, writing an editorial in the local newspaper, targets a very specific group of people, people who read the newspaper. So, you'll really only be targeting people who read the newspaper. And who knows? That might be very few people.
Now, if you go with option C, making flyers and giving them out to people, nobody is going to care. In this day and age, if I were to get a poster or something, I would just throw it away, and 99% of humanity is exactly like me. We don't want a ton of posters. We're not going to look at them. We'll toss them in the trash.
But if you go with the televised press conference, not only will you be communicating directly with the public, but you'll be putting it on television, which is much simpler and, frankly, a more entertaining way to engage the public then with a newspaper article.
Plus, if you go with option C and print a ton of posters, you'll sort of be contradicting your own message of trying to preserve the environment by wasting a ton of paper.