What is the primary component of Mars's atmosphere?

The primary component of Mars's atmosphere is carbon dioxide. Mars has a very thin atmosphere, composed of about 95% carbon dioxide, which is significantly higher than the concentrations found in Earth's atmosphere. This high proportion of carbon dioxide contributes to the greenhouse effect, although it is not strong enough to significantly warm the planet.

In contrast, the other components listed are present in much smaller quantities in Mars's atmosphere. Oxygen and nitrogen, both abundant in Earth's atmosphere, make up only trace amounts on Mars. Argon does exist in a low concentration, but it is still far less than carbon dioxide. Understanding the composition of Mars's atmosphere is crucial for studying its climate, potential for past or present life, and its geological history.