When you don't understand the question that the examiner poses, don't freak out.
You could say something like, "Could you please repeat the question?"; "Would you mind rephrasing the question?"; or "Sorry, what was that last word?"
Don't ask for repetition or explanation of a question more than once.
It's better to answer as much about the question as you understand rather than not to answer at all. So if you know the question has something to do with your opinion about the environment, you can make as good of a guess about the specifics of the topic rather than not answer at all. You can also say something like, "Sorry, I'm not very familiar with that topic because. . ."
Reference: https://magoosh.com/ielts/clarification-ielts-speaking/
If you're interested in practicing with an IELTS speaking teacher, send me a PM, and I'll be glad to help.