Which one of the following conditions is most relevant for the presence of life on Mars ?

The most relevant condition for life on Mars is the presence of water, represented here by the occurrence of ice caps and frozen water. All known life requires liquid water, so “follow the water” is the guiding principle in assessing habitability; searching for past or present liquid water leads to the best prospects for life detection [2]. Geological and spacecraft evidence indicates Mars may once have had liquid water—perhaps lakes—and thus conditions potentially suitable for simple life forms in the past [1]. Today much of Mars’ water exists as polar ice and subsurface/seasonal brines; these reservoirs (or their transient melting) are the key targets for habitability studies, even though atmospheric and thermal factors influence water stability.

Sources

1. [2] https://geo.libretexts.org/Bookshelves/Geography_(Physical)/BioGeoChemistry_(LibreTexts)/02%3A_Origins/2.06%3A_Earthlike_Planets_-_Venus_and_Mars/2.6.05%3A_Water_and_Life_on_Mars
2. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 13: Our Home: Earth, a Unique Life Sustaining Planet > Did Mars ever support life? > p. 215