produces the least carbon dioxide per unit energy when combusted

Of course, if you want to choose one of your own photographs, pictures or an image you find on a website as your background, find the image and right-click on its icon. Choose "Set image as desktop background" and it will become your new theme. To save it as a theme for future use, open the Personalize option again and click "Save theme." Now you can reuse it again and again without having to hunt for the original image. Before going into battle a soldier should prepare. To wear the proper armour and obtain hold of a shield and sword. The armour protects from harm as well as the sword kills unhealthy guy. You also must be fighting fit. It's the same once you battle against yourself. You need protection from dangerous illusions and also to be with right knowledge and understanding.