Since it is a controversial question, there is no correct or incorrect answer. You are not supposed to know whether they do or not. I don't know the exam, but I assume this is an essay question and you are writing out an answer in words and sentences for a human being to read. The point of an "opinion" question would be to see, not only whether you can use grammar correctly, but also to see whether you can express a complicated idea in a way that can be understood. So, two reasonable answers could be "Big buildings cause environmental damage by concentrating too many people in too small an area and putting too much load on the water and sewer systems." Or, "Big buildings are good for the environment because they can be designed to be heated and cooled more efficiently and are likely to be better maintained."

I'm not sure whether this is a speaking or writing question, but there are a number of strategies to deal with this... and I do teach these strategies. The main thing is being able to express yourself in English clearly and with reasoning. There's no point in having a good answer if you can't put it in a sentence.