The correct response is: The temperature of Earth’s surface would decrease because more heat would escape into space.
Here's the reasoning: Carbon dioxide (CO2) is a greenhouse gas that plays a significant role in trapping heat in the atmosphere. If the proportion of CO2 decreases significantly, there would be less greenhouse gas available to absorb and re-radiate heat. Consequently, more heat would escape into space, which would likely lead to a decrease in the Earth's surface temperature.