Liquid water, an energy source, and organic compounds are the three main things that are needed to support life. Planet X and Jupiter’s moon, Io are very interesting celestial bodies that could have life living on it. Although I think one planet is more likely to support life than the other, I think that life would be more likely on Planet Z than Io. Also, Planet Z has more of the requirements for life than Io. Another reason is that Planet Z has more Earth-like qualities which makes it a better choice than Planet Z.
Liquid water is extremely important here on Earth, water helps to transport substances, and liquid water is a need for supporting life. One reason why Planet Z is more suitable to support life than Io is