Final answer:
Mercury, Venus, and Mars are not likely to support life as we know it due to extreme temperatures, unsuitable atmospheric conditions, and lack of geological activity required for supporting life.
Step-by-step explanation:
Why Mercury, Venus, and Mars Are Not Likely to Support Life
Mars, Venus, and Mercury are unlikely to support life as we know it due to various inhospitable conditions.
Venus is extremely hot and dry, with a thick, toxic atmosphere consisting mostly of carbon dioxide and a surface pressure far exceeding that on Earth. Its surface temperature can melt lead, making it unlikely to support Earth-like life.
Mars is on the other extreme, being cold and dry. It has a thin atmosphere mostly comprised of carbon dioxide. While there is evidence of past water flows, current conditions are harsh, with surface life-supporting abilities having dwindled billions of years ago.
Mercury is also inhospitable, with extreme temperatures fluctuating between very hot and very cold. It lacks a substantial atmosphere to moderate these temperatures or to provide breathable air. Moreover, Mercury is geologically dead, lacking the geological activity that might support a dynamic, life-sustaining environment.
Even when planets like Venus are within the habitable zone, the lack of water and other essential conditions for life as we know it, precludes their habitability.