Answer:
the correct answer is CO2 (the last one)
The answer to fill in the blank would be B) because say for ex you are sick and your mom checks your temperature, she is doing this to see how hot/cold are you, so she is checking your body to see how you are, so same with this, temperature basically measures the kinetic energy/motion of particles in something.
The barometer would show a decrease in wind speed resulting in the disipation of cloud cover because of the lack of wind, and also because the temperature is dropping there is less precipation because there is no hot air rising to create clouds :)
Air is a mixture of several gasses
Photosynthesis is how producers make their own food