What was the climate like during the Hesperian Period?

The Hesperian Period, which is one of the geological periods of Mars, is characterized by significant climatic changes compared to the preceding Noachian Period. During the Hesperian, Mars underwent a transformation where temperatures became colder and the atmosphere became thinner than it was before.

This colder climate is believed to be related to a reduction in volcanic activity and possibly changes in solar radiation affecting the planet. The thin atmosphere would struggle to retain heat, contributing to the general cooling trend observed during this period. The conditions that prevailed were not conducive to the kinds of stable or humid environments that may have existed in earlier or later periods, leading to a more arid landscape dominated by fluvio-lacustrine systems and erosion features.

In contrast, the other options describe climates that do not align with the geological evidence observed on Mars during the Hesperian Period. Therefore, the depiction of a colder climate with a thinner atmosphere accurately reflects the characteristics of Mars during this time, which are supported by geological and atmospheric studies from various Mars missions.