Which ecosystem? Stupid question?

The Guardian reported a debate hosted by Earthwatch a few nights ago at the Royal Geographic Society about our most vital ecosystem asking "If you could only save one ecosystem for the good of the planet, would it be forests, wetlands, oceans, mountains or the polar regions?" Speakers were allocated to make the case for each and it sounds like it went down well. Whether an online audience is always a bit more grumpy than a face-to-face audience or whether it just lacks something in the telling I'm not sure. The unanimous response online seems to be that it's a stupid question. As one commenter put it - a bit like saying which one organ of the body would you keep if you could only choose one....i.e. they're all important, what sense does it make just to choose one?