If we removed the atmosphere's natural greenhouse effect, and everything else stayed the same, Earth's temperature would be:

A. 10 to 20°F (6 to 11°C) warmer

B. B. 30 to 40°F (17 to 22°C) warmer

C. 10 to 20°F (6 to 11°C) cooler

D. 50 to 60°F (28 to 33°C) cooler​