If Earth Were to Warm Up a Bit,what Would Happen

If Earth were to warm up a bit,what would happen?

A) Carbonate materials would form in the oceans more rapidly,the atmospheric CO₂ content would decrease,and the greenhouse effect would weaken slowly over time.
B) Carbonate materials would form in the oceans more slowly,the atmospheric CO₂ content would increase,and the greenhouse effect would strengthen slowly over time.
C) Carbonate materials would form in the oceans more rapidly,the atmospheric CO₂ content would decrease,and the greenhouse effect would strengthen slowly over time.
D) There would be a runaway greenhouse effect,with Earth becoming ever hotter until the oceans evaporated (as may have happened on Venus) .
E) The ice caps would melt and cool Earth back to its normal temperature.