Which of these statements best describes how an increase in atmospheric carbon dioxide contributes to global climate change? select one: a. water bodies dry up and cause less rainfall. b. forest fires become frequent which heats the earth. c. plant growth becomes rapid which increases rainfall worldwide. d. more sunlight is trapped by the atmosphere to cause global warming.

I believe the answer is D.  More sunlight is trapped by the atmosphere to cause global warming.
Even though Atmosphere usually contains Co2, the amount is really minor and heat from the Sunlight usually still able to reflected outside under noermal circumtances. But, due to usage of fossil fuels, the amount of CO2 in the atmosphere is significantly increased and making the sunlight unable to reflected outside and trapped within the Earth.