Question

Martian Soil Activity Models

During the 1976 Viking Lander missions, scientists observed chemical activity when Martian soil samples were mixed with a liquid nutrient solution. Two scientists proposed competing hypotheses to explain this observation.

*Scientist 1*
The soil activity is biological. Martian soil contains microscopic organisms that metabolize organic nutrients. When these organisms consume the nutrients, they release carbon dioxide ($CO_2$) gas. Heating the soil to $160^\circ\text{C}$ kills these organisms, which is why preheating the soil prevents gas release.

*Scientist 2*
The soil activity is inorganic. Highly reactive oxygen-carrying chemicals, such as superoxides, are present in the soil due to exposure to intense ultraviolet radiation. When mixed with the liquid solution, these superoxides chemically oxidize the nutrients, releasing $CO_2$. Heating the soil to $160^\circ\text{C}$ thermally decomposes the superoxides, rendering them unable to react with nutrients.

According to Scientist 1's hypothesis, what is the primary agent responsible for the release of carbon dioxide gas from the soil mixture?