Without the Greenhouse Effect Operating in Our Atmosphere

Multiple Choice

Without the greenhouse effect operating in our atmosphere,

A) the Earth would have become much more like Venus long ago.
B) we would not have to worry about any warming problems in the future.
C) the ice in the polar regions would have melted long ago.
D) the ozone layer would not be weakening.
E) Earth would have an average temperature of - 23 degrees Celsius.