Wich planet(s) in our solar system do you think life can survive on?
The most likely candidate is Mars. The Earth is a rocky planet, so it seems sensible to look for life on other rocky planets too. We can ignore Mercury, because it's too close to the Sun, so it's too hot. And Pluto is too cold and far away to support life. Out of all the planets in the Solar System, Mars is most like Earth. And it's also the most likely to contain life.
The giant gassy planets have no solid surface on which life could roam. But could life still fly around in the atmosphere of a gassy planet?