An astronomer studying planets outside our solar system has analyzed the atmospheres of four planets. which of these planets’ atmospheres would be most able to support a colony of humans?

What planets are you talking about? Well, the one with a good level of oxygen ( allows humans to breath and forms the ozone layer that protects us from the Suns harmful rays) and hydrogen( mixes with oxygen to make water). The suns impact on the planet affects the whole life on it, so you need to take that into consideration. List me the four planets and I can give you a much better explanation.