Earth's average surface temperature has risen by about 1 °F over the past 30 years. The primary cause of this is increasing levels of:
A. Solar irradiance
B. Water vapor in the atmosphere
C. Carbon dioxide in the atmosphere
D. Methane in the atmosphere
E. Nitrous oxide in the atmosphere
F. Chlorofluorocarbons (CFCs) in the atmosphere
G. Ozone in the atmosphere