Previous Year Question

Among the given planets, Mars is considered the most suitable for studying the possibility of life. The major reason is the evidence of ancient river valleys, deltas and lakebeds on its surface, indicating that liquid water probably existed there for long periods in the past.

NASA's Curiosity rover has found evidence in Gale Crater of ancient conditions that could have been habitable for microbial life. Rock samples there contain chemical elements essential for life, including sulfur, nitrogen, oxygen, phosphorus and carbon, while clay minerals also indicate that relatively fresh water once existed there.

However, this does not mean that life has been discovered on Mars. Present-day Mars is extremely cold and dry and has a very thin atmosphere, so liquid water cannot remain stable on its surface for long. Scientists are primarily investigating whether Mars once had conditions suitable for life and whether microbial life ever arose there.

Therefore, compared with Mercury, Venus and Jupiter, Mars is the correct answer in the context of the question.