I want to know the answer to the following question:
What did the marchers wish to commemorate?
All the background I'm provided with is that "On April 26, 1988, about 500 people participated in a march organized by the Ukrainian Cultural Club on Kiev's Khreschatyk Street to mark the second anniversary of the Chernobyl nuclear disaster, carrying placards with slogans like "Openness and Democracy to the End."". Is that enough to answer the question?
Answer: yes