26. Which is most important to put in the summary? (A) In Helsinki, Finland, about 3,000 students gathered with signs about dinosaurs. (B) Thousands of people marched to demand an end to coal burning in Poland. (C) Around the world, students have been skipping school on Fridays to make leaders pay attention to climate change. (D) In December 2018, Greta Thunberg spoke at a climate meeting in Poland.